Multifocal Contact Lenses And Related Methods And Uses To Improve Vision Of Presbyopic Subjects

ABSTRACT

Multifocal contact lenses and methods and uses are described. The multifocal contact lenses include an optic zone. The optic zone has an aspheric power profile that provides a near vision refractive power and a distance vision refractive power, and provides an Add power that corresponds to the difference between the near vision refractive power and the distance vision refractive power. The multifocal contact lenses can improve binocular vision of presbyopic subjects by being prescribed such that the non-dominant eye contact lens is over-corrected for distance vision, and both multifocal contact lenses are under-corrected for the Add power requirement of the subject. Batches and sets of multifocal contact lenses are also described.

This application claims the benefit under 35 U.S.C. §119(e) of priorU.S. Provisional Patent Application No. 61/594, 859 filed Feb. 3, 2012,which is incorporated in its entirety by reference herein.

FIELD

The present disclosure is directed to multifocal contact lenses andmethods of making and using multifocal contact lenses, as well asbatches and sets of multifocal contact lenses.

BACKGROUND

Contact lenses have been described as being useful in correctingpresbyopia. Some methods and devices for treating presbyopia orimproving vision of presbyopic subjects have been described, such as inEP0201231A1, EP2183639A1, GB2086605A, U.S. Pat. No. 5,220,359, U.S. Pat.No. 5,715,031, U.S. Pat. No. 5,754,270, U.S. Pat. No. 5,771,088, U.S.Pat. No. 5,835,192, U.S. Pat. No. 6,322,213, U.S. Pat. No. 6,520,638,U.S. Pat. No. 6,540,353, U.S. Pat. No. 7,517,084, U.S. Pat. No.7,625,086, U.S. Pat. No. 7,753,521, US20090051870A1, US20100321632A1,US2011310347A1, WO0008516, and WO0135880.

As one example, in a monovision correction system, a presbyopic personwears one contact lens having a design for only correcting distancevision in one eye (e.g., the lens has a single labeled sphere power tocorrect distance vision), and a second contact lens having a design foronly correcting near vision in the other eye (e.g., the lens has asingle labeled sphere power to correct near vision). Monovisioncorrection seems to provide better results for presbyopic subjectsrequiring low Add power correction (e.g., low Add patients). Higher Addsubjects tend to experience more visual discomfort or visual compromisewith monovision systems, such as blurred images and the like.

As another example, multifocal contact lenses having aspheric optics toprovide a relatively smooth transition in optical power across the lens,or multifocal contact lenses with distinct optical zones that alternatebetween distance and near refractive powers have also been described asbeing useful for correcting presbyopia. Examples of contact lenses forcorrecting presbyopia include: the ACUVUE OASYS for Presbyopia(Vistakon, Jacksonville, Fla., USA; lens pairs consisting of twocenter-distance lenses); the PUREVISION MULTIFOCAL (Bausch & Lomb,Rochester, N.Y., USA; lens pairs consisting of two center-near frontsurface aspheric lenses); the AIR OPTIX AQUA MULTIFOCAL (Ciba Vision,Duluth, Ga., USA; lens pairs consisting of two center-near asphericlenses); and FREQUENCY 55 MULTIFOCALS, PROCLEAR MULTIFOCALS, andBIOFINITY MULTIFOCALS (each from CooperVision, Pleasanton, Calif., USA;lens pairs consisting of a center-distance lens and a center-near lens).

Although multifocal contact lenses provide vision improvement to manypresbyopic subjects, multifocal contact lenses can produce secondaryimages or “ghost” images, as perceived by the subject. This ghosting islikely to be attributed to defined zones and/or narrow transitionsbetween distance and near powers of the multifocal contact lenses. Itremains a challenge to provide both clear distance visual acuity andclear near visual acuity to the subject, let alone do so and reduce oravoid visual discomfort or visual compromise, such as ghosting, contrastloss, and the like. This challenge is especially true for subjectsrequiring medium or high Add powers in contact lenses (such as subjectsrequiring an Add power correction greater than +1.00 diopter).

To address this challenge and meet the requirements of eye carepractitioners (ECPs) and presbyopic subjects, contact lens manufacturerscurrently offer multiple lens choices for an ECP to select from andprescribe. Although the relatively large number of options available tothe ECP and subject or patient appears beneficial, the large number ofoptions can reduce the efficiency of the ECP by requiring more time tofind the desired lens combination for a particular subject from amongthe large number of options. Providing large number of lens combinationsto ECPs is also undesirable for a contact lens manufacturer, ordistributor, or both because the increased number of lens designs andcombinations for different sphere powers and Add powers result inincreased inventory that must be made and stored to provide to the ECPor the subject.

Based on the increasing number of presbyopic people, there continues tobe a need for new multifocal contact lenses which provide effectivevision correction to presbyopic people.

SUMMARY

The present invention addresses a need in the art to provide multifocalcontact lenses that provide a desired amount of distance visual acuityand near visual acuity, without significantly compromising the distancevisual acuity and without unduly introducing additional visualcompromise, especially for presbyopic subjects requiring more than +1.00diopters of Add power (e.g., medium Add and high Add presbyopicsubjects). As used herein, a presbyopic subject is understood to be aperson who is presbyopic, and the phrase “presbyopic subject” is usedinterchangeably with presbyope. If the presbyopic subject is a patientof an eye care practitioner (ECP), that presbyopic subject may bereferred to herein as a presbyopic patient. At the same time, thepresent invention addresses a need to simplify the fitting process ofmultifocal contact lenses for ECPs and to simplify the manufacture ofthe multifocal contact lenses by contact lens manufacturers.

The present invention is based on the discovery that multifocal contactlenses that utilize an aspheric power profile in the optic zone within acertain range or within certain parameters, as discussed herein, canprovide binocular visual acuity that is better than that attained withexisting multifocal contact lenses without introducing additional visualcompromise, such as ghosting, contrast loss, and the like, even thoughmonocular visual acuity at near and far viewing distances in either eye(e.g., only one eye) is less than the binocular visual acuity at nearand far viewing distances.

As discussed herein, with the present lenses and present methods, apresbyopic subject, such as a medium Add or high Add presbyope, ismonocularly optimally or best corrected for distance vision in thedominant eye of the subject, monocularly over-corrected for distancevision in the non-dominant eye of the subject, and is binocularlyunder-corrected for Add power (i.e., under-correcting the Add power inboth lenses). As one non-limiting example, provided for purposes ofillustration only, a myopic presbyope may require a prescription of−3.00 diopters (D) to correct distance vision in each eye (i.e., thenon-dominant eye and the dominant eye), and may require an Add power of+1.75 D to correct the lack of accommodation associated with presbyopia.In accordance with the present disclosure, the presbyope would beprescribed a multifocal contact lens, as described herein, for thedominant eye that has a distance vision refractive power of −3.00 D andan Add power that is less than +1.75 D (such as, a lens having an Addpower that is a value from +0.75 D to +1.50 D), and would be prescribeda lens for the non-dominant eye that has a distance vision refractivepower that is more positive than −3.00 D (such as, a lens labeled ashaving a distance vision refractive power that is a value from −2.75 Dto −1.75 D) and an Add power that is less than +1.75 D (such as, a lenslabeled as having an Add power that is a value from +0.75 D to +1.50 D).For example, the Add power in such lenses could be +0.75 D, +1.00 D,+1.25 D, or +1.50 D. A higher Add presbyope requiring an Add power ofgreater than +2.00 D may be prescribed lenses having an Add power ofabout +1.75 D or +2.00 D, as a further example. As used herein, adistance vision refractive power refers to the optical power of thecontact lens that is effective in correcting distance vision of apresbyope; the phrase distance vision refractive power is usedinterchangeably with the term distance power, as used in the art. Inaddition, the word “a” or “an”, as used herein, means one or more, andis synonymous with “at least one”. A plurality refers to two or more,and is synonymous with “multiple”. The term including, as used herein,is an open-ended term which is intended to have the same meaning ascomprising.

With the present multifocal contact lenses, methods, and uses, it ispossible for a presbyope to utilize the visual processing of the brainto compensate for the reduced monocular visual acuity and provide aperceived superior binocular visual acuity compared to the monocularvisual acuity provided by either lens alone. As described herein, thiscan be achieved by providing an aspheric multifocal contact lens for thedominant eye of a presbyope, and by providing a similar asphericmultifocal contact lens for the non-dominant eye of the presbyope, butthe lens for the non-dominant eye has a distance vision refractive powerthat is more positive than the presbyope's distance vision refractionnecessary to provide a visual acuity of 20/30 or 20/20 or better. Forexample, by providing a multifocal contact lens of the multifocalcontact lenses described herein for the presbyope's non-dominant eyethat has a distance vision refractive power that is +0.25 to +1.25diopters more positive than the presbyope's distance vision requirement,the presbyope's binocular visual acuity improves compared to hismonocular visual acuity due to binocular summation. That is, themonocular refractive blur caused by the over-corrected lens on thenon-dominant eye has little impact on binocular visual acuity, and thepresbyope perceives distant images as determined by combined images fromthe lenses in the dominant eye and non-dominant eye, which is of betterimage quality than the individual images from either eye. The degradedimage of the non-dominant eye resulting from the over-correction of thedistance vision of the non-dominant eye, can actually add to and improvethe contrast of the image from the dominant eye.

As described in more detail herein, the present multifocal contactlenses each have an aspheric power profile in the optic zone thatattempts to reduce or minimize the change in power across the opticzone, and particularly, the central 5 mm diameter portion of the opticzone and still provide a binocularly acceptable distance vision and nearvision visual acuity. The aspheric power profile is designed to providean effective Add power while also providing a rate of change that is nottoo steep so as to maintain sufficient near vision correction across thecentral portion of the optic zone and to reduce visual disturbances,such as ghost images, flares, and the like. The improved clinicalresults observed with the present multifocal contact lenses and methodsand uses are related to monocularly balancing contrast loss andover-correction (i.e., in only one eye), but by under-correcting the Addpower binocularly (i.e., in both eyes of a subject). This combinationhelps reduce contrast loss binocularly. As can be appreciated from thepresent description, a new system and methods for improving vision ofpresbyopic subjects or presbyopes are described, and which providesimplicity for a contact lens manufacturer by reducing inventoryrequirements, provide simplicity for an ECP by reducing the number ofeffective options for the ECP to choose and fit to a presbyope, andthereby reduce the chair time of the presbyope to achieve a successfulimprovement in vision, and provide sufficient binocular distance visualacuity and near visual acuity without introducing additional visualcompromise. These improvements are related to the shape of the asphericpower profile, the reduced variability in power profiles across lensesof different distance vision refractive powers, an effective amount ofmonocular over-correction of the distance vision refractive power for anon-dominant eye, and an effective amount of binocular under-correctionof the Add power of the presbyope.

In one aspect, the present invention relates to multifocal contactlenses (e.g., two or more multifocal contact lenses). Furthermore, inthis aspect, the present invention relates to methods of using themultifocal contact lenses, such as methods of supplying multifocalcontact lenses to eye care practitioners (ECPs), methods of supplyingmultifocal contact lenses to presbyopic subjects, methods of fittingpresbyopic subjects with multifocal contact lenses, and methods ofimproving vision or visual acuity of presbyopic subjects with thepresent multifocal contact lenses. In this context, the multifocalcontact lenses and methods can be understood to relate to perspectivesof ECPs, contact lens manufacturers, contact lens distributors, contactlens retailers, or presbyopic subjects, or combinations thereof.

In accordance with the foregoing aspect, the multifocal contact lensesinclude a first multifocal contact lens for the dominant eye of thepresbyopic subject, and a second multifocal contact lens for thenon-dominant eye of the presbyopic subject. Each of the first multifocalcontact lens and the second multifocal contact lens includes an opticzone. The optic zone is circumscribed by a peripheral zone. The opticzone has an optic zone center and an optic zone perimeter spacedradially away from the optic zone center and defining a boundary betweenthe optic zone and the peripheral zone. The optic zone has an asphericpower profile extending from the optic zone center towards the opticzone perimeter and provides a near vision refractive power and adistance vision refractive power, or distance power as used in the art,such that each of the multifocal contact lenses has an Add power. TheAdd power is the absolute difference in power between the near visionrefractive power and the distance vision refractive power (thus, as usedherein, the Add power is always a positive number). In accordance withthis aspect of the present invention, the first multifocal contact lenshas a distance vision refractive power effective in providing thepresbyopic patient with a high contrast visual acuity of 20/30 (Snellennotation) or better for the dominant eye at a viewing distance of atleast 6 meters. In terms of diopters (D), the distance vision refractivepower can be from +20.00 D to −20.00 D, and the appropriate distancevision refractive power is selected to provide the presbyopic subjectwith the desired distance visual acuity. The second multifocal contactlens has a near vision refractive power effective in providing thepresbyopic subject with a high contrast visual acuity of 20/30 (Snellennotation) or better for the non-dominant eye at a viewing distance ofabout 60 centimeters or less. The second multifocal contact lens alsohas a distance vision refractive power that is offset by about +0.25diopters to about +1.25 diopters relative to the distance powercorrection for the non-dominant eye of the presbyopic subject. Inaccordance with this aspect and the present teachings, the binocularvisual acuity provided to the presbyopic subject by the pair of thefirst and second multifocal contact lenses worn simultaneously isgreater than the monocular visual acuity provided to the presbyopicsubject by either the first multifocal contact lens or the secondmultifocal contact lens, alone.

Additional features in accordance with the foregoing aspect will beappreciated from the following detailed description, drawings, examples,and claims.

In a second aspect, the present invention relates to a batch or batchesof multifocal contact lenses, and methods of manufacturing a batch orbatches of multifocal contact lenses. In this context, the batch orbatches of multifocal contact lenses and the present methods can beunderstood to relate to the perspective of a contact lens manufacturer.

In accordance with this second aspect, a batch of multifocal contactlenses for improving vision of presbyopic subjects is provided. Thebatch includes, consists essentially of, or consists of, a plurality ofmultifocal contact lenses (e.g., two or more), which can be provided inpackages. Each of the multifocal contact lenses includes an optic zone,and a peripheral zone, as described above. The optic zone has an opticzone center and an optic zone perimeter spaced radially away from theoptic zone center and defining a boundary between the optic zone and theperipheral zone. The optic zone has an aspheric power profile extendingfrom the optic zone center towards the optic zone perimeter andproviding a near vision refractive power and a distance visionrefractive power such that each of the multifocal contact lenses has anAdd power, wherein the Add power is the absolute difference in powerbetween the near vision refractive power and the distance visionrefractive power, as described herein. The plurality of multifocalcontact lenses includes a plurality of first multifocal contact lensgroups. Each first multifocal contact lens group includes multifocalcontact lenses providing a unique single distance vision refractivepower for the first multifocal contact lens group (e.g., one group has adistance vision refractive power of −2.00 D, and a second group has adistance vision refractive power of −3.00 D, etc.). The aspheric powerprofile of each of said multifocal contact lenses within a singlecontact lens group provides a single Add power selected from a valuefrom about 0.75 diopters to 2.00 diopters over a radial distance of 2.5mm from the optic zone center for each lens of the series. For example,each multifocal contact lens of a single contact lens group may have asingle Add power of 0.75 D, 1.00 D, 1.25 D, 1.50 D, 1.75 D, or 2.00 D asmeasured along a 2.5 mm radius from the optic zone center. The Add powerprovided by the aspheric power profile of the individual multifocalcontact lenses of any of the first multifocal contact lens groups variesby no more than ±0.25 D compared to the Add power provided by a relativeaspheric power profile of the plurality of multifocal contact lenses. Asused herein, the relative aspheric power profile is the average of powerprofiles of the plurality of multifocal contact lenses and in which thedistance vision refractive power at a radial distance of 2.5 mm is fixedat 0.00 diopters. Thus, the aspheric power profile is normalized suchthat the optical power of the lens at a radial distance of 2.5 mm is0.00 D. The Add power of individual multifocal contact lenses of thegroup can vary by plus or minus (±) 0.25 D from the relative asphericpower profile. Thus, if the relative aspheric power profile has an Addpower of 1.10 D, individual multifocal contact lenses may have Addpowers from 0.85 D to 1.35 D. The aspheric power profile of theindividual multifocal contact lenses of any of the first multifocalcontact lens groups also have similar shapes. In particular, theaspheric power profiles differ by no more than ±0.375 D compared to therelative aspheric power profile of the plurality of multifocal contactlenses along the power profile for each radial distance measured alongthe power profile. Thus, along the radial distance of 2.5 mm, theindividual power profiles do not vary by more than 0.375 D in eitherdirection (positive or negative). In the methods of manufacturing thebatch or batches of multifocal contact lenses, the methods include astep of forming the plurality of multifocal contact lenses from apolymerizable composition (e.g., lens formulation). The contact lensesmay be lathed contact lenses, in which the aspheric power profile islathed directly on to the polymer, may be static cast molded contactlenses, where the aspheric power profile is machined on to a metalinsert that is used to form contact lens molds, or may be spun castcontact lenses, in which the aspheric power profile is machined onto ametal insert used to shape a single mold surface on which apolymerizable composition is placed to cure.

Additional features in accordance with the second aspect will beappreciated from the following detailed description, drawings, examples,and claims.

In a third aspect, the present invention relates to a set or sets ofmultifocal contact lenses for improving vision of presbyopic subjects.As one example, a set of this aspect may be understood to be a fittingset of the present multifocal contact lenses. As described further, aset of multifocal contact lenses includes a dominant eye series and anon-dominant eye series (e.g., multifocal contact lenses for placementon either the dominant eye or non-dominant eye of the subject,respectively). The dominant eye series and non-dominant eye series canbe presented as two distinct series of lenses, each with their owndistance refractive powers. Or, the dominant eye series and thenon-dominant eye series can be presented as a single set of lenses,where an ECP selects a first multifocal contact lens from the set forplacement on the subject's dominant eye, and the ECP selects a secondmultifocal contact lens from the set for placement on the subject'snon-dominant eye. In accordance with this third aspect, methods ofproviding multifocal contact lenses are also disclosed. In this context,the set or sets of multifocal contact lenses and the present methods canbe understood to relate to the perspective of a contact lensmanufacturer, an ECP, a contact lens distributor, or a contact lensretailer.

In accordance with this third aspect, a set of multifocal contact lensesfor improving vision of presbyopic subjects is provided. A set, asdescribed herein, includes, consists essentially of, or consists of, (i)a dominant eye series of multifocal contact lenses and (ii) anon-dominant eye series of multifocal contact lenses. Each of themultifocal contact lenses in each series includes an optic zone that hasan optic zone center and an optic zone perimeter. The optic zoneperimeter is spaced radially away from the optic zone center and definesa boundary between the optic zone and a peripheral zone. The optic zonehas an aspheric power profile extending from the optic zone centertowards the optic zone perimeter and provides a near vision refractivepower and a distance vision refractive power such that each of saidmultifocal contact lenses has an Add power. As described herein, the Addpower is the absolute difference in power between the near visionrefractive power and the distance vision refractive power. The dominanteye series includes a plurality of dominant eye patient lens setscorrelating to Add power requirements of presbyopic subjects or patients(e.g., two or more patient lens sets, which can be labeled as beinguseful for medium Add and high Add subjects, low Add and medium Addsubjects, low Add and high Add subjects, or low Add subjects, medium Addsubjects, and high Add subjects). The plurality of patient lens setsincludes a first dominant eye patient lens set that includes multifocalcontact lens groups. The groups include multifocal contact lensesproviding unique distance vision refractive powers, as described herein.Each group includes at least one multifocal contact lens (i.e., one ormore multifocal contact lenses). The aspheric power profile of each ofthe multifocal contact lenses of the dominant eye patient lens setprovides a single Add power selected from a value from about 0.75diopters to 2.00 diopters over a radial distance of 2.5 mm from theoptic zone center for each lens of the series. The Add power provided bythe aspheric power profile of individual multifocal contact lenses ofthe first dominant eye patient lens set varies by no more than ±0.25diopters compared to the Add power provided by a relative aspheric powerprofile of the multifocal contact lenses of the first dominant eyepatient lens set. As described herein, the relative aspheric powerprofile is the average of power profiles of a plurality of multifocalcontact lenses of the first dominant eye patient lens set and in whichthe distance vision refractive power at a radial distance is fixed at0.00 diopters.

The non-dominant eye series of the foregoing set or sets also includes aplurality of patient lens sets correlating to Add power requirements ofpresbyopic subjects or patients. The plurality of patient lens setsincludes a first non-dominant eye patient lens set including multifocalcontact lenses, wherein each of the multifocal contact lenses of thefirst non-dominant eye patient lens set having an aspheric power profilethat provides a single Add power selected from a value from about 0.75diopters to 2.00 diopters over a radial distance of mm from the opticzone center for each lens of the first non-dominant eye patient lensset, so long as the distance vision refractive power provided by theaspheric power profile of the multifocal contact lenses of the firstnon-dominant eye patient lens set is offset by about +0.25 diopters toabout +1.25 diopters relative to the distance power correction for apresbyopic subject.

A method in accordance with this third aspect includes a step ofmanufacturing the plurality of multifocal contact lenses to have anaspheric power profile in the optic zone, as described herein. Themanufactured multifocal contact lenses are packaged in contact lenspackages. The packaged multifocal contact lenses, as described herein,are provided to a contact lens distributor, a contact lens retailer, oran ECP, or combinations thereof. The packaged multifocal contact lensesso provided include a dominant eye series and a non-dominant eye series,as described above.

Additional features in accordance with the third aspect will beappreciated from the following detailed description, drawings, examples,and claims.

In a fourth aspect, the present invention provides methods of using thepresent multifocal contact lenses. For example, a method of prescribingmultifocal contact lenses to a presbyopic subject are described. In thiscontext, such methods can be understood to relate to the perspective ofan ECP or other individual or entity that prescribes contact lenses topeople.

In accordance with this fourth aspect, a method of prescribingmultifocal contact lenses to a presbyopic subject includes a step offitting the presbyopic subject with a pair of multifocal contact lenses.The presbyopic subject so fit requires an Add power correction of atleast 1.25 D (e.g., from 1.25 D to 3.00 D). A first multifocal contactlens of the pair includes a first aspheric power profile derived from afirst nominal aspheric power profile. A second multifocal contact lensof the pair includes a second aspheric power profile derived from thefirst nominal aspheric power profile, but the second aspheric powerprofile provides or has a distance vision refractive power offset byabout +0.25 D to about +1.25 D relative to the distance power correctionfor the non-dominant eye of the presbyopic subject. With such a fitting,monocular distance visual acuity is different for each eye with eachcontact lens, and binocular summation is still maintained when the firstand second contact lenses are worn simultaneously. The method mayoptionally include fitting a second pair of multifocal contact lenseswhere the first multifocal contact lens of the second pair has the sameaspheric power profile as the first aspheric power profile of the firstmultifocal contact lens, and the second contact lens of the second pairhas an aspheric power profile that provides an area under the curve(AUC) that is between 5% and 45% greater than the AUC of the asphericpower profile of the first multifocal contact lens of the second pair.The methods may also include a step of conducting an eye examination todetermine ocular dominance. The methods may also include a step ofdetermining a prescription of the presbyopic subject and prescribing thefirst and second multifocal contact lenses to the presbyopic subject.

Additional features in accordance with the fourth aspect will beappreciated from the following detailed description, drawings, examples,and claims.

Additional aspects and embodiments of the present lenses, batches, sets,methods, and uses will be apparent from the following description,drawings, examples, and claims. As can be appreciated from the foregoingand following description, each and every feature described herein, andeach and every combination of two or more of such features, is includedwithin the scope of the present invention provided that the featuresincluded in such a combination are not mutually inconsistent. Inaddition, any feature or combination of features may be specificallyexcluded from any embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1F illustrate multifocal contact lenses in accordance with thepresent invention. FIG. 1A is an illustration of a first multifocalcontact lens. FIG. 1B is an illustration of a second multifocal contactlens. FIG. 1C illustrates an aspheric power profile from the center ofthe optic zone of the lens (0 mm) to about the optic zone perimeter(radial distance of about 4.1 mm) of the contact lens of FIG. 1A. FIG.1D illustrates an aspheric power profile from the center of the opticzone of the lens (0 mm) to about the optic zone perimeter (radialdistance of about 4.1 mm) of the contact lens of FIG. 1B. FIG. 1E is amagnified view of FIG. 1C illustrating the aspheric power profile for aradial distance of 2.5 mm. FIG. 1F is a magnified view of FIG. 1Dillustrating the aspheric power profile for a radial distance of 2.5 mm.

FIG. 2A illustrates an aspheric power profile of a Lens A in accordancewith the present invention, and an aspheric power profile of a Lens B asa comparative. The shaded portion depicts the area under the curve (AUC)of the aspheric power profile of Lens A.

FIG. 2B illustrates an aspheric power profile of a Lens A in accordancewith the present invention, and an aspheric power profile of a Lens B asa comparative. The shaded portion depicts the area under the curve (AUC)of the aspheric power profile of Lens B.

FIG. 3 is a graph illustrating logMAR values as a measure of visualacuity of medium Add subjects under high illumination and high contrastconditions for Lens A and Lens B of FIGS. 2A and 2B.

FIG. 4 is a graph illustrating logMAR values as a measure of visualacuity of medium Add subjects under low illumination and low contrastconditions for Lens A and Lens B of FIGS. 2A and 2B.

FIG. 5 is a graph illustrating logMAR values as a measure of visualacuity of high Add subjects under high illumination and high contrastconditions for Lens A and Lens B of FIGS. 2A and 2B.

FIG. 6 is a graph illustrating logMAR values as a measure of visualacuity of high Add subjects under low illumination and low contrastconditions for Lens A and Lens B of FIGS. 2A and 2B.

FIG. 7 is a table of different visual acuity scales, as understood bypersons or ordinary skill in the art.

FIG. 8 is an illustration of a set of multifocal contact lenses inaccordance with the present invention.

FIG. 9 is an illustration of a manufacturing method useful in themanufacture of the multifocal contact lenses, batches thereof, groupsthereof, and sets thereof, in accordance with the present invention.

FIGS. 10A-10D illustrate a batch of multifocal contact lenses inaccordance with the present invention. FIG. 10A illustrates a batch thatincludes multiple groups of multifocal contact lenses, each groupcorresponding to a unique distance refractive power. FIG. 10Billustrates aspheric power profiles for three multifocal contact lensesin accordance with the present invention. The shaded region depicts theamount of variability of the power profile along the radial distancethat individual lenses may have, and still be understood to be withinthe teachings of the present invention. FIG. 10C illustrates the Addpower for the three lenses of FIG. 10B. The Add power can vary byplus/minus 0.25 diopters (D). FIG. 10D illustrates aspheric powerprofiles of three of the present multifocal contact lenses, each havinga unique distance vision refractive power (i.e., −1.50 D, −3.00 D, and-4.00 D).

FIG. 11A illustrates a second group of multifocal contact lenses, usefulwith the batch illustrated in FIG. 10A. FIG. 11B illustrates an asphericpower profile for a multifocal contact lens (Lens C) of the second groupof FIG. 11A, which has an AUC greater than Lens A, and less than Lens B.

FIG. 12 is an illustration of the rate of power change over a radialdistance of 2.5 mm, for Lens A, Lens B, and Lens C of FIG. 11B.

FIG. 13 is an illustration of a set of multifocal contact lenses similarto FIG. 8.

DETAILED DESCRIPTION

As described herein, the present invention is based on the discoverythat multifocal contact lenses that include an optic zone that has anaspheric power profile to provide an Add power correction can be usedand made to provide presbyopic subjects with a desired amount ofdistance visual acuity and a desired amount of near visual acuitywithout unduly compromising or negatively affecting the distance visualacuity, and without unduly introducing additional visual compromise,especially for presbyopes requiring more than +1.00 diopters (D) of Addpower correction (e.g., medium Add and high Add presbyopes). With thepresent multifocal contact lenses and the present methods, a presbyopicsubject, such as a medium Add or high Add presbyope, is monocularlyoptimally or best corrected for distance vision in the dominant eye ofthe subject, and monocularly over-corrected for distance vision in thenon-dominant eye of the subject, and is binocularly under-corrected forAdd power relative to the Add power correction needed by the presbyope(e.g., without including the over-correction of the non-dominant eye).In accordance with the present teachings, the present multifocal contactlenses improve near vision without unduly disturbing distance vision,and without unduly introducing additional ghosting compared to currentlyexisting bifocal and multifocal contact lens products. With the presentmultifocal contact lenses, a balance of distance vision and near visionbetween both eyes provides improved multifocal vision to presbyopes.Unlike monovision systems, which create cortical summation loss, themultifocal contact lenses of the present invention maintain binocularcortical summation. As used herein, binocular cortical summation orbinocular summation refers to an increase in the binocular responsecompared with the monocular respone, when the sensitivities of thedominant eye and non-dominant eye are equal, as described by Pardhan etal., Optometry and Vision Science (1990), Vol. 67, No. 9, pp. 688-691,Binocular inhibition: psychophysical and electrophysiological evidence;and Pardhan et al., Ophthal. Physiol. Opt., (1990), Vol. 10, January,33-36, The effect of monocular defocus on binocular contrastsensitivity. Unlike existing bifocal and multifocal systems, which tendto cause more visual compromise, such as ghosting, contrast loss, andthe like, for medium Add and high Add presbyopes, the multifocal contactlenses of the present invention not only provide clear distance visualacuity and clear near visual acuity, but do so without introducingadditional vision compromise.

Multifocal contact lenses are described herein. The present multifocalcontact lenses are useful in improving or correcting vision of apresbyopic subject. As understood by persons of ordinary skill in theart, the presbyopic subject has a dominant eye and a non-dominant eye.Ocular dominance can be determined by an eye care practitioner (ECP)using conventional methods, such as the “lens fogging” technique, theMiles test, the Porta test, the Dolman method, the Pinhole test, and thelike. Presbyopia typically begins to manifest in people forty years ofage or older. Presbyopes are frequently grouped into low Add groups(requiring up to 1.00 diopter (D) of Add power correction); medium Addgroups (requiring from 1.25 D to 1.75 D of Add power correction); orhigh Add groups (requiring from 2.00 D or more of Add power correction).Frequently, high Add presbyopes require an Add power correction lessthan 3.00 D.

The multifocal contact lenses described herein include a firstmultifocal contact lens and a second multifocal contact lens. As usedherein, the first multifocal contact lens is for the dominant eye of thepresbyope, and the second multifocal contact lens is for thenon-dominant eye of the presbyope. That is, each contact lens will beplaced on the respective eye of the presbyopic subject.

Each of the first multifocal contact lens and the second multifocalcontact lens includes an optic zone. The optic zone of each has an opticzone center and an optic zone perimeter. The optic zone perimeter isspaced radially away or apart from the optic zone center. The optic zoneperimeter defines a boundary or border between the optic zone and aperipheral zone of the contact lens. The optic zone, as defined by theoptic zone perimeter, can be visualized using conventional lensinspection devices and techniques, such as interferometers, and thelike.

The optic zone of each multifocal contact lens has an aspheric powerprofile. The aspheric power profile extends from the optic zone centertowards the optic zone perimeter. With the aspheric power profile, anear vision refractive power and a distance vision refractive power isprovided, and accordingly, the multifocal contact lenses each have anAdd power. The present multifocal contact lenses can be center-distanceaspheres or center-near aspheres. A center-distance asphere is amultifocal contact lens in which the distance vision refractive power,or distance power, is located in the center of the lens. A center-nearasphere is a multifocal contact lens in which the near vision refractivepower, or near power, is located in the center of the lens. The distancepower corresponds to the portion of the power profile that is relativelymore negative, and the near power corresponds to the portion of theprofile that is relatively more positive. For purposes of simplicity,the following description will be based on multifocal contact lensesthat are center-near aspheres. It is to be understood that the presentmultifocal contact lenses and methods are not limited to multifocalcontact lenses that are center-near aspheres, unless specificallystated.

As used herein, the Add power is the absolute difference in powerbetween the near vision refractive power and the distance visionrefractive power. The near power zone of the aspheric power profilecorresponds to a region of the profile (or the optic zone) where theoptical power is the most positive. In the context of the presentdisclosure, including the illustrated embodiments of multifocal contactlenses, the near power zone refers to a central zone of the optic zonehaving a 2 mm diameter (1 mm radial distance from the optic zonecenter). The distance power zone of the aspheric power profilecorresponds to a region of the profile (or the optic zone) where theoptical power is the most negative. In the context of the presentdisclosure, including the illustrated embodiments, the distance powerzone refers to a zone circumscribing the central zone and beginning at1.25 mm from the optic zone center and extending to 2.25 mm from theoptic zone center. The near power of the near power zone refers to theaverage power of the near power zone. The distance power of the distancepower zone refers to the average power of the distance power zone. Thus,the Add power of the present multifocal contact lenses can be understoodto be the absolute difference between the average distance power and theaverage near power. The Add power of the present multifocal contactlenses, including multifocal contact lenses of the present batches andsets disclosed herein, can be at least 0.50 D. In the embodimentsdescribed further herein, the Add power of the multifocal contact lensesis from about 0.75 D to no greater than 2.00 D. For example, the Addpower may be about 0.75 D, about 1.00 D, about 1.25 D, about 1.50 D,about 1.75 D, or 2.00 D. Preferably, the Add power of the presentmultifocal contact lenses has a value between 0.75 D and 2.00 D.

The first multifocal contact lens of the multifocal contact lenses has adistance vision refractive power effective in providing the presbyopicsubject with a high contrast visual acuity of 20/30 (Snellen notation)or better for the dominant eye at a viewing distance of at least 6meters. In other words, the first multifocal contact lens is optimallyor best corrected for distance vision for the dominant eye of thepresbyopic subject and provides clear high contrast visual acuity at farviewing distances (i.e, 6 meters or more). Visual acuity is measuredusing conventional techniques, as understood by persons of ordinaryskill in the art. For example, the visual acuity can be determined usinga Snellen eye chart or a logMAR chart during the course of an eyeexamination. FIG. 7 illustrates visual acuity scales, such as theSnellen notation in feet, meters, or decimal notation, as well as thecorresponding logMAR values. The distance vision refractive power refersto a refractive power required for achieving the presbyopic subject'ssubjective best distance correction for the dominant eye.

The second multifocal contact lens has a near vision refractive powereffective in providing the presbyopic subject with a high contrastvisual acuity of 20/30 (Snellen notation) or better for the non-dominanteye at a viewing distance of about 60 centimeters or less, such as about40 cm, for example. In other words, the second multifocal contact lensprovides clear or acceptable high contrast visual acuity to thepresbyopic subject at near viewing distances (e.g., 60 cm or less). Thenear vision refractive power is the amount of optical power necessary tocorrect the subject's near visual acuity. In addition, the secondmultifocal contact lens has a distance vision refractive power that isoffset by about +0.25 D to about +1.25 D relative to the distance powercorrection for the non-dominant eye of the presbyopic subject. Thedistance vision refractive power of the second multifocal contact lensin accordance with the present invention can be offset by +0.25 D, +0.50D, +0.75 D, +1.00 D, or +1.25 D, relative to the distance powercorrection of the non-dominant eye. In certain embodiments, includingthe illustrated embodiments, the offset of the distance visionrefractive power of the second multifocal contact lens is +0.75 D or+1.00 D.

The combination of the first and second multifocal contact lensesdescribed hereinabove provide binocular visual acuity to the presbyopicsubject that is greater than the monocular visual acuity provided to thepresbyopic subject by either the first multifocal contact lens or thesecond multifocal contact lens, alone. As described herein, with respectto the results of the Examples, with the present multifocal contactlenses, lens pairs (i.e., first and second multifocal contact lenses)can be provided to presbyopic subjects to improve their vision bymaintaining binocular cortical summation for any age of subject (e.g.,40 years to 70 years, etc.).

An example of the present multifocal contact lenses 10 is illustrated inFIGS. 1A-1F. A first multifocal contact lens 12 is illustrated in FIG.1A, and a second multifocal contact lens 22 is illustrated in FIG. 1B.The first multifocal contact lens 12 includes an optic zone 14 and aperipheral zone 17, which circumscribes the optic zone 14. The opticzone 14 has an optic zone center 11 and an optic zone perimeter 13spaced radially away from the optic zone center 11. A radius 15 isillustrated as extending from the optic zone center 11 to the optic zoneperimeter 13. The second multifocal contact lens 22 includes an opticzone 24 and a peripheral zone 27, which circumscribes the optic zone 24.The optic zone 24 has an optic zone center 21 and an optic zoneperimeter 23 spaced radially away from the optic zone center 21. Aradius 25 is illustrated as extending from the optic zone center 21 tothe optic zone perimeter 23.

In embodiments of the present multifocal contact lenses, the optic zonehas a diameter from about 7.00 mm to about 9.00 mm, and thus, theradius, such as radius 15 or radius 25, may be from 3.5 mm to 4.5 mmfrom the optic zone center. As shown in FIGS. 1C and 1D, the asphericpower profiles 19 and 29 of the multifocal contact lenses 12 and 22,respectively, are illustrated over a radius of about 4.1 mm, such thatthe optic zone diameter of each multifocal contact lens is about 8.2 mm.FIG. 1E is a magnified illustration of FIG. 1C depicting the asphericpower profile over a radial distance of 2.5 mm. FIG. 1F is a magnifiedillustration of FIG. 1D depicting the aspheric power profile over aradial distance of 2.5 mm. As discussed herein, the emphasis of thepresent disclosure is on the 2.5 mm radius of the optic zone andaspheric power profile since many presbyopes have pupils with diametersthat dilate to approximately 5.0 mm. Therefore, the central 5.0 mmdiameter of the optic zone is significant in influencing acceptance ofthe vision correction provided by the multifocal contact lenses.

As shown in FIGS. 1C-1F, the aspheric power profiles are relatively morepositive towards the center of the lens (i.e., the center of the lenshas a more positive optical power than the periphery), and thus, themultifocal contact lenses 12 and 22 can be understood to be near-centeraspheres. In other words, the optical power of the lens is more negativein the periphery of the optic zone relative to the center of the opticzone. In addition, the aspheric power profiles 19 and 29 have beennormalized such that the distance vision refractive power is set to 0 D.This has been done for purposes of illustration, only. In practice, amultifocal contact lens of the present invention, and having a distancepower of −3.00 D would actually have an aspheric power profile with thepower at a 2.5 mm radial distance being about −3.00 D.

Thus, it can be understood that the aspheric power profiles illustratedherein are provided for purposes of illustration only to complement theteachings of the present application. In addition, the illustratedaspheric power profiles may be understood to correspond to nominal ortarget power profiles used in the design of the present multifocalcontact lenses, or may be understood to be representative of a relativeaspheric power profile, as defined herein. Actual power profiles formultifocal contact lenses as measured using optical instruments may varyfrom the illustrated profiles, similar to those power profiles shown inFIG. 10D. Further, since the aspheric power profiles illustrated hereinare normalized to 0.0 D at a radial distance of 2.5 mm, these profilesdo not account for the true optical power of each lens (e.g., the actualdistance power for the different lenses, such as −3.00, −2.00, −1.50 D,etc.), or the over-correction of the non-dominant eye lenses.

The aspheric power profile of multifocal contact lenses can be measuredor determined using conventional equipment and methods, such as by usinginterferometers, wavefront sensors, and the like, as understood bypersons of ordinary skill in the art. Some examples of suitablewavefront sensors include those provided by Optocraft (Erlangen,Germany) or Rotlex (Omer, Israel), or a Shack-Hartmann wavefront sensor(Clear-Wave, Abott Medical Optics-Wavefront Sciences, Albuquerque, N.Mex., USA). In addition, the aspheric power profile of the presentmultifocal contact lenses can be described or characterized by anysuitable mathematical function or equation, as understood by persons ofordinary skill in the art. For example, the aspheric power profile ofthe multifocal contact lenses of the present invention may berepresented by an even order polynomial, a Zernike polynomial, and thelike.

With the present multifocal contact lenses, the aspheric power profileof the first multifocal contact lens and the aspheric power profile ofthe second multifocal contact lens provide a difference in high contrastvisual acuity between the first multifocal contact lens and the secondmultifocal contact lens that is at least one line of a Snellen visualacuity chart or a logMAR visual acuity chart at a viewing distance of atleast 6 meters.

With the present multifocal contact lenses, the aspheric power profileof the first multifocal contact lens and the aspheric power profile ofthe second multifocal contact lens provide a difference in high contrastvisual acuity between the first multifocal contact lens and the secondmultifocal contact lens that is less than half a line of a Snellenvisual acuity chart or a logMAR visual acuity chart at a viewingdistance from about 60 centimeters to about 1.5 meters (i.e.,intermediate distances).

With the present multifocal contact lenses, the aspheric power profileof the first multifocal contact lens and the aspheric power profile ofthe second multifocal contact lens provide a difference in high contrastvisual acuity between the first multifocal contact lens and the secondmultifocal contact lens that is at least one line of a Snellen visualacuity chart or a logMAR visual acuity chart at a viewing distance nogreater than 60 centimeters (i.e., near viewing distances).

As mentioned herein, any of the preceding multifocal contact lenses caninclude a first multifocal contact lens and a second multifocal contactlens that have distance vision refractive powers effective in providingdifferent monocular distance visual acuity for each eye with eachcontact lens, and binocular summation is still maintained when thelenses are simultaneously worn.

In addition to providing an Add power correction, embodiments of thepresent multifocals may include a cylinder correction to correct asubject's astigmatism. Thus, either the first multifocal contact lens,or the second multifocal contact lens, or both may include a tonic opticzone having a cylinder power effective in correcting astigmatism of thepresbyopic subject. Some non-limiting examples of cylinder powers thatare useful in the present toric multifocal contact lenses include −0.75D, −1.25 D, −1.75 D, −2.25 D, and −2.75 D, as well as cylinder powershaving values between any of these listed powers. Thus, the presenttoric multifocal contact lenses can have a cylinder power having a valuefrom −0.75 D to −2.75 D. As discussed herein, if the toric multifocalcontact lenses are provided in a series of lenses, the series can havecylinder powers from −0.75 D to −2.75 D, or any subset thereof, such as−0.75 D to −2.25 D, −1.00 D to −2.25 D, and the like.

The present multifocal contact lenses can be either hard contact lensesor soft contact lenses. Preferably, the multifocal contact lenses aresoft contact lenses. As used herein, a soft contact lens is a contactlens that can be folded upon itself without breaking. The presentmultifocal contact lenses can be hydrogel contact lenses. As usedherein, a hydrogel contact lens refers to a hydrated contact lens thathas an equilibrium water content (EWC) of at least 10%. Frequently, theEWC is between 20% and 90%, and preferably, the EWC of the presentmultifocal contact lenses is between 30% and 70%. The present contactlenses can also be silicone hydrogel contact lenses. As used herein, asilicone hydrogel contact lens is a hydrogel contact lens that includesa silicon or silicone component. Examples of some of the hydrogel orsilicone hydrogel lens formulations useful for the present multifocalcontact lenses have United States Adopted Names (USANs) of etafilcon A,nelfilcon A, hilafilcon A, methafilcon A, ocufilcon A, ocufilcon B,ocufilcon C, ocufilcon D, omafilcon A, balafilcon A, lotrafilcon A,lotrafilcon B, galyfilcon A, senofilcon A, narafilcon A, narafilcon B,comfilcon A, etafilcon A, or stenfilcon A.

FIG. 2A and FIG. 2B illustrated aspheric power profiles for twodifferent multifocal contact lenses, Lens A and Lens B. Lens A isrepresented by an aspheric power profile providing an Add power between1.00 D and 1.25 D. Lens B is represented by an aspheric power profileproviding an Add power of about 2.00 D. The shaded region of FIG. 2Acorresponds to the area under the curve (AUC) of Lens A. The shadedregion of FIG. 2B corresponds to the AUC of Lens B. The AUC of Lens B isabout 47% greater than the AUC of Lens A. This can be attributed to theincreased Add power and the greater rate of change in diopters/mm (e.g.,analogous to slope) observed for the Lens B power profile. In accordancewith the present disclosure, the present multifocal contact lenses havepower profiles that provide AUCs similar to Lens A or less than 147% ofthe AUC of Lens A (e.g., less than the AUC of the power profile of LensB). The AUC of any power profile can be calculated using anyconventional technique, such as the Trapezoid Rule, Simpson's 1/3 Rule,or Integration of a Regression Equation. In the present application, theTrapezoid Rule was used to calculate the AUC. In brief, the curves aredivided into a series of trapezoids, each trapezoid having an area. TheAUC corresponds to the sum of the areas of the trapezoids. An example ofthe equation used to calculate the AUC can be described as: AUC=(sum oftwo adjacent Y values)/2)×(the difference of two adjacent X values),where Y corresponds to diopters and X corresponds to millimeters, asshown in the Figures.

As described below, including the Examples, distance visual acuity issignificantly improved for presbyopes wearing a pair of Lens Amultifocal contact lenses, in accordance with the present disclosure, ascompared to the same presbyopes wearing a pair of Lens B multifocalcontact lenses. Intermediate visual acuity is improved for Lens Awearers under high illumination, high contrast conditions, compared toLens B wearers. In addition, despite the binocular under-correction ofAdd power, the near vision provided by pairs of Lens A lenses to Lens Awearers is substantially the same as the near vision provided by pairsof Lens B lenses to Lens B wearers. This is observed for both medium Addand high Add presbyopic subjects. For example, FIG. 3 illustrates logMarvalues for medium Add presbyopes wearing a pair of Lens A lenses, inaccordance with the present invention, or Lens B lenses, as acomparative, under high illumination and high contrast conditions. Asunderstood by persons of ordinary skill in the art, a relatively morenegative logMAR value is indicative of better or clearer visual acuity.Thus, values less than 0 logMAR, which corresponds to 20/20 in Snellennotation, indicate better visual acuity than values greater than 0logMAR. As shown in FIG. 3, Lens A wearers have improved distance andintermediate visual acuity, and comparable near visual acuity, comparedto the same wearers wearing pairs of Lens B lenses. As shown in FIG. 4,distance visual acuity is better for Lens A wearers than Lens B wearersunder low illumination and low contrast, and near vision was equal.

FIG. 5 is similar to FIG. 3 but for high Add presbyopes. As shown inFIG. 5, high Add Lens A wearers have improved distance visual acuityunder high illumination and high contrast, with comparable intermediateand near visual acuities. FIG. 6 is similar to FIG. 4 but for high Addpresbyopes. As shown in FIG. 6, high Add Lens A wearers have improveddistance visual acuity and equal near visual acuity under lowillumination and low contrast.

With respect to FIGS. 3-6, high and low illumination refer to therelative lighting within the area of the visual acuity assessment, andhigh contrast and low contrast refer to the relative contrast of lettersbeing read compared to the background of the letters, as understood bypersons of ordinary skill in the art.

Thus, as shown in FIGS. 3-6, the multifocal contact lenses of thepresent invention provide substantial improvements in visual acuity(e.g., good distance vision and near vision, without compromisingdistance vision) in medium Add and high Add presbyopes compared tomultifocal contact lenses that have relatively higher Add powers (e.g.,about 2.00 D or more) and that have aspheric power profiles with AUCsthat are at least about 47% greater than the AUC of the aspheric powerprofile of the multifocal contact lenses of the present invention.

The multifocal contact lenses of the present invention can bemanufactured in a variety of ways. For example, the contact lenses canbe lathed from polymer rods or buttons, where a lathe is used to machinethe aspheric power profile onto a surface of the polymer rod or button.Or, the contact lenses can be spun cast, where a single female mold isformed, such as by injection molding, and which has a concave surfacehaving the aspheric power profile for the present contact lenses. Or,the contact lenses can be static cast molded, which involvespolymerizing a lens formulation or polymerizable composition between amale and female mold member. In a preferred method, the contact lensesare static cast molded, as described herein in reference to FIG. 9.

FIG. 9 illustrates a static cast molding manufacturing method 100. Themethod begins by forming optical inserts at step A. This forminginvolves lathing an optical surface onto a surface of a metallic insert(represented as 101 in FIG. 9) with a tip of a lathe 103. Lathed opticalinserts are then placed in a plate 105 of an injection molding machine107. A second plate 109 is moved into contact with plate 105 to formcontact lens mold cavities near the optical insert at Step B. Moldforming material, such as polystyrene, polypropylene, or vinyl alcoholmold forming materials, are injection molded into the contact lens moldcavities, to produce a male mold member 111 and a female mold member113. At step C, a volume of polymerizable composition can be dispensedon the concave surface of the female mold member 113. At step D, themale and female mold members are placed in contact with each other toform a contact lens mold assembly 115 having a contact lens shapedcavity 117 containing the polymerizable composition. At step E, contactlens mold assemblies are placed in a curing system 119 that allows thepolymerizable composition to polymerize. Polymerization is usuallycarried out using heat, ultraviolet light, or a combination thereof. Thecontact lens mold assemblies are removed from the curing system 119 andthe male and female mold members are demolded, or separated from eachother. The polymerized contact lens product remains attached to eitherthe male mold member of the female mold member. In FIG. 9, thepolymerized contact lens product 121 remains attached to the concavesurface of the female mold member. The polymerized contact lens productis delensed, or separated, from the female mold member at Step F. Thedelensing can be done using a liquid, or it can be done mechanicallywithout use of a liquid. The delensed contact lens product is placed ina cavity of a primary contact lens package 123 at Step G. In FIG. 9, theprimary contact lens package is a blister pack. At step H, the blisterpack is sealed and sterilized by autoclaving and the like. Thesterilized blister packs 125 are placed in secondary packaging 127 atStep I, which in FIG. 9 is illustrated as a carton. The secondarypackaging can then be placed in a cabinet device 129 at Step J, such asfor a fitting set of lenses, as described herein, or can be packaged intertiary packaging for shipment or storage.

In accordance with the present invention, a method of supplyingmultifocal contact lenses for a presbyopic subject to an ECP isprovided. As described herein, the presbyopic subject has a dominanteye, and a non-dominant eye, which can be determined by an ECP. Thepresent method includes a step of manufacturing the multifocal contactlenses of the present invention, as described herein. The method furtherincludes a step of providing the multifocal contact lenses to an eyecare practitioner for fitting the presbyopic subject with the firstmultifocal contact lens and the second multifocal contact lens. Asdescribed herein, the first multifocal contact lens provided to the ECPhas a distance vision refractive power effective in providing thepresbyopic subject with a high contrast visual acuity of 20/30 or betterat a viewing distance of at least 6 meters, and the second multifocalcontact lens has a near vision refractive power effective in providingthe presbyopic subject with a high contrast visual acuity of 20/30 orbetter at a viewing distance of about 60 centimeters or less, and has adistance vision refractive power that is offset by about +0.25 D toabout +1.25 D relative to the distance power correction for thenon-dominant eye of the presbyopic subject. The binocular visual acuityprovided to the presbyopic subject by the pair of the first and secondmultifocal contact lenses worn simultaneously is greater than orimproved relative to the monocular visual acuity provided to thepresbyopic subject by either the first multifocal contact lens or thesecond multifocal contact lens, alone. Thus, the binocular visual acuityis better than either of the monocular visual acuities at distant andnear viewing distances.

In another method, a method of supplying multifocal contact lenses to apresbyopic subject is provided. Such a method includes a step ofreceiving an order for the multifocal contact lenses, as describedherein, such as the first and second multifocal contact lenses describedabove, or as illustrated in FIGS. 1A-1F. After receiving the order, themethod includes a step of providing the multifocal contact lenses to thepresbyopic subject. As described herein, the first multifocal contactlens provided to the ECP has a distance vision refractive powereffective in providing the presbyopic subject with a high contrastvisual acuity of 20/30 or better at a viewing distance of at least 6meters, and the second multifocal contact lens has a near visionrefractive power effective in providing the presbyopic subject with ahigh contrast visual acuity of 20/30 or better at a viewing distance ofabout 60 centimeters or less, and has a distance vision refractive powerthat is offset by about +0.25 D to about +1.25 D relative to thedistance power correction for the non-dominant eye of the presbyopicsubject. The binocular visual acuity provided to the presbyopic subjectby the pair of the first and second multifocal contact lenses wornsimultaneously is greater than or improved relative to the monocularvisual acuity provided to the presbyopic patient by either the firstmultifocal contact lens or the second multifocal contact lens, alone. Insome methods, the receiving step optionally includes a step of receivinga prescription of the presbyopic subject for the first and secondmultifocal contact lenses.

Another method of using the present multifocal contact lenses relates tofitting a presbyopic subject with the multifocal contact lenses. Amethod of fitting a presbyopic subject includes a step of selecting afirst multifocal contact lens for the dominant eye of the presbyopicsubject, and a step of selecting a second multifocal contact lens forthe non-dominant eye of the presbyopic subject. Each of the first andsecond multifocal contact lenses are as described above, and the firstmultifocal contact lens has a distance vision refractive power effectivein providing the presbyopic subject with a high contrast visual acuityof 20/30 or better for the dominant eye at a viewing distance of atleast 6 meters, and the second multifocal contact lens has a near visionrefractive power effective in providing the presbyopic subject with ahigh contrast visual acuity of 20/30 or better for the non-dominant eyeat a viewing distance of about 60 centimeters or less, and has adistance vision refractive power that is offset by about +0.25 dioptersto about +1.25 diopters relative to the distance power correction forthe non-dominant eye of the presbyopic subject. The binocular visualacuity provided to the presbyopic subject by the pair of multifocalcontact lenses worn simultaneously is greater than the monocular visualacuity provided by either multifocal contact lens, alone. The method mayalso include a step of determining which eye of the presbyopic subjectis the dominant eye. The method may also include a step of prescribingthe first and second multifocal contact lenses to the presbyopicsubject.

Another method of using the multifocal contact lenses of the presentinvention relates to improving vision of a presbyopic subject. A methodof improving vision of a presbyopic subject includes a step of providingany of the multifocal contact lenses of the present invention to thepresbyopic subject. The contact lenses are provided for selfadministration by the subject to his or her own eyes. In some regions,the method may include the proviso that the step of administration bythe subject is not part of the present methods of the invention.

In the foregoing methods, the first and second multifocal contact lenseshave distance vision refractive powers effective in providing differentmonocular distance visual acuity for each eye with each contact lens(e.g., the dominant eye is fully corrected for distance vision, and thenon-dominant eye is over-corrected for distance vision), and binocularsummation is still maintained.

Any of the multifocal contact lenses of the present invention may beused in the methods described herein, and in certain embodiments, thefirst and second multifocal contact lenses are near-center asphericmultifocal contact lenses; in certain embodiments, one or both of thefirst and second multifocal contact lenses includes a toric optic zoneeffective in correcting astigmatism of the presbyopic subject; and incertain embodiments, the multifocal contact lenses are hydrogel orsilicone hydrogel contact lenses.

Another aspect of the present invention relates to batches of multifocalcontact lenses, as discussed herein. In the manufacture of the presentmultifocal contact lenses on a commercial scale, it is desired toproduce multiple contact lenses in parallel and accumulating the contactlenses so produced in batches. Typically, the contact lenses are alsoaccumulated in groups of single distance powers, such that they can bepackaged in secondary packaging containing one or more lenses of thesame distance power. As can be appreciated, due to manufacturingtolerances and instrument variability in measuring power profiles, theaspheric power profiles of the present multifocal contact lenses mayappear slightly different than the nominal or target power profile usedto design the lenses. Unlike some existing multifocal contact lenses,which show dramatic differences in Add powers across groups ofmultifocal lenses with different distance powers, or show differences inpower profile shapes across groups of multifocal contact lenses withdifferent distance powers, the present batches are produced such thatmultifocal contact lenses within a group are substantially similar toeach other. For example, the Add power of the multifocal contact lensescan vary by plus or minus (±) 0.25 D, and the aspheric power profile canvary by ±0.375 D along the radial distance of the power profile. Thus,multiple groups of multifocal contact lenses can be produced inaccordance with the present invention based on a single nominal ortarget aspheric power profile used in the design of the multifocalcontact lenses.

Accordingly, a batch of multifocal contact lenses of the presentinvention includes a plurality of multifocal contact lenses. Each of themultifocal contact lenses includes an optic zone having an optic zonecenter and an optic zone perimeter spaced radially away from the opticzone center. The optic zone perimeter defines a boundary between theoptic zone and a peripheral zone of the contact lens. The optic zone hasan aspheric power profile extending from the optic zone center towardsthe optic zone perimeter and provides a near vision refractive power anda distance vision refractive power such that each of said multifocalcontact lenses has an Add power. As described herein, the Add power isthe absolute difference in power between the near vision refractivepower and the distance vision refractive power.

The plurality of multifocal contact lenses of the batch include aplurality of first multifocal contact lens groups. For example, theplurality of multifocal contact lenses can be divided into multifocalcontact lens groups. As one example, if a plurality of contact lenses is1,000 contact lenses, the plurality can include 10 groups of 100 contactlenses. Each of the first multifocal contact lens groups includesmultifocal contact lenses that have a unique single distance visionrefractive power corresponding to the distance power label for the firstmultifocal contact lens group. As one example, the first multifocalcontact lens groups can include one group of multifocal contact lenseshave a distance power of −3.00 D, one group of multifocal contact lenseshaving a distance power of −3.25 D, one group of multifocal contactlenses having a distance power of −3.50 D, one group of multifocalcontact lenses having a distance power of −3.75 D, one group ofmultifocal contact lenses having a distance power of −4.00 D, and so on.The first multifocal contact lens groups can have multifocal contactlenses having distance powers from +20.00 D to −20.00 D in 0.25 Dincrements (in other words, the groups can have multifocal contactlenses having a single distance power from +20.00 D to −20.00 D, or anyvalue therebetween).

As described above, within the first multifocal contact lens groups, theaspheric power profile of each of the multifocal contact lenses within asingle group, e.g., having a single distance power, is substantiallysimilar to each other. For example, the total amount of Add powerprovided by the aspheric power profile is substantially similar, and theshape of the aspheric power profile is substantially similar. Thesimilarity derives from the use of a single nominal or target asphericpower profile in the design of the multifocal contact lenses ofindividual groups.

More specifically, the aspheric power profile of each of the multifocalcontact lenses within a single contact lens group provides an Add powerselected from a value from about 0.75 D to 2.00 D over a radial distanceof 2.5 mm from the optic zone center for each lens of the group. The Addpower may be 0.75 D, 1.00 D, 1.25 D, 1.50 D, or 1.75 D, for example. TheAdd power for any individual multifocal contact lenses varies by no morethan ±0.25 D compared to the Add power provided by a relative asphericpower profile of the plurality of multifocal contact lenses. As usedherein, the relative aspheric power profile refers to the average ofpower profiles of the plurality of multifocal contact lenses within thesingle group, and in which the distance vision refractive power at aradial distance of 2.5 mm is fixed at 0.00 D.

In addition, the aspheric power profiles have similar shapes. Morespecifically, the aspheric power profile of the individual multifocalcontact lenses of any of the first multifocal contact lens groupsdiffers by no more than ±0.375 D compared to the relative aspheric powerprofile of the plurality of multifocal contact lenses within a singlegroup along the power profile for each distance measured. For example,if the optical power of the lens is measured along a radius of 2.5 mm in0.05 mm increments, the optic power at any of those 0.05 mm incrementsis within 0.375 D from the optic power of the relative aspheric powerprofile at the same position.

As an illustration of the batches of multifocal contact lenses of thepresent invention, reference is made to FIGS. 10A to 10D. FIG. 10Aillustrates a batch 40 of multifocal contact lenses. The batch 40includes a plurality 42 of multifocal contact lenses. The plurality 42of multifocal contact lenses includes a plurality of first multifocalcontact lens groups 44. Each multifocal contact lens group 44 hasmultifocal contact lenses providing a unique single distance visionrefractive power. These unique single powers are represented in FIG. 10Aas −3.00 D, −3.25 D, −3.50 D, −3.75D, and −4.00 D, by way of example andnot limitation. Accordingly, in the first multifocal contact lens group44 labeled with a −3.00 D distance vision refractive power, themultifocal contact lens or lenses within that group each of a distancepower of about −3.00 D.

FIG. 10B illustrates the similarity of power profiles for the multifocalcontact lenses within a single group. The power profile labeled as LensA is similar to the power profile illustrated in FIGS. 1E and 1F.However, in FIG. 10B, the Lens A power profile represents the relativeaspheric power profile described above. In other words, it is theaverage of the power profiles for the individual multifocal contactlenses within the group, and the distance power at a radial distance of2.5 mm is 0.00 D. The shaded region represents the spread of ±0.375 Dfrom the relative aspheric power profile. Two other multifocal powerprofiles are illustrated by the lines labeled Lens A′ and Lens A″. Eachof these aspheric power profiles are within the 0.375 D tolerance fromthe relative aspheric power profile, as described above, and therefore,are examples of multifocal contact lenses of the present batches.

FIG. 10C illustrates the Add power of the relative aspheric powerprofile (Lens A), and the two multifocal contact lenses (Lens A′ andLens A″). The error bars for the Lens A Add power reflect the toleranceof ±0.25 D of the Add power of the relative aspheric power profile. Boththe Lens A′ and Lens A″ have Add powers within the 0.25 D tolerance.

FIG. 10D illustrates an example of aspheric power profiles of themultifocal contact lenses of the batches of the present invention butfor three different groups. One trace is for a group with multifocalcontact lenses that have a distance power of −1.50 D, one trace is for agroup with multifocal contact lenses that have a distance power of −3.00D, and one trace is for a group with multifocal contact lenses that havea distance power of −4.00 D. As can be appreciated from FIG. 10D, evenacross different lens groups (e.g., different distance powers), theaspheric power profiles of embodiments of multifocal contact lenses ofthe present invention are substantially similar.

In accordance with the present disclosure, in some embodiments of thepresent batches of the invention, a batch includes a plurality ofmultifocal contact lenses that also includes a plurality of secondmultifocal contact lens groups. Briefly, the multifocal contact lensesof the second multifocal contact lens groups have aspheric powerprofiles that are different than the aspheric power profiles of themultifocal contact lenses of the first multifocal contact lens groups.In more detail, the second multifocal contact lens groups includemultifocal contact lenses that provide a unique single distance visionrefractive power, as described above for the first groups. Each of themultifocal contact lenses of the second multifocal contact lens groupshave an aspheric power profile that provides an AUC that is between 5%to 45% greater than an AUC of the relative aspheric power profile of themultifocal contact lenses of the first multifocal contact lens groups.

An example of such second contact lens groups is illustrated in FIG. 11Aat reference number 52. The second contact lens groups 52 is similar tothe first contact lens groups 42 except that the multifocal contactlenses of the second contact lens group 52 have a different powerprofile than those of the first contact lens group 42. As describedherein, multifocal contact lenses having a power profile similar to theLens B power profile illustrated in FIG. 11B do not perform as well forvisual acuity compared to the multifocal contact lenses of the presentinvention, such as multifocal contact lenses having a power profilesimilar to that represented as Lens A in FIG. 11B. In accordance withthis second multifocal contact lens group, the multifocal contact lensescan have an aspheric power profile as referenced by Lens C in FIG. 11B.The power profile of Lens C provides an AUC (shaded region) that isbetween 5% and 45% greater than the AUC provided by the power profilefor Lens A. Lenses of the second multifocal contact lens group with suchpower profiles are useful in further improving the vision of presbyopesrequiring 2.00 D or more of Add power correction.

In some embodiments, the AUC of the multifocal contact lens groups isless than 35% greater than the AUC of the relative aspheric powerprofile of the multifocal contact lenses of the first multifocal contactlens groups.

As discussed herein, not only is the amount of Add power important withthe present teachings, but the rate of change in optic power over theradius of 2.5 mm is important. It is believed that the greater the rateof change (e.g., a steeper slope), the greater visual discomfort isprovided to the presbyopic subject since the transition from near powerto distance power is greater over a shorter distance. For example,visually, it is apparent that the slope of the power profile of Lens Bof FIG. 11B at about 0.75 mm to about 1.5 mm is steeper than thecorresponding slope for the Lens A power profile.

FIG. 12 illustrates the rate of power change (D/mm) as a function ofradial position for the Lens A, Lens B, and Lens C power profiles ofFIG. 11B. The rate of power change is determined by calculating thefirst order derivative of each of the power profiles.

FIG. 12 illustrates that the absolute value of maximum rate of powerchange for Lens A is about 0.7 to 0.8 D/mm, for Lens C is about 0.9D/mm, and for Lens B is about 1.5 D/mm.

Thus, in accordance with the present teachings, in any of the batches ofthe present invention, some embodiments provide individual multifocalcontact lenses that have aspheric power profiles with a maximum rate ofpower change having an absolute value greater than 0.0 D/mm and lessthan 0.9 D/mm.

As discussed herein, the mutifocal contact lenses of the batches of thepresent invention can be provided as lens pairs that are effective toprovide an improved visual acuity to a presbyopic subject compared tothe visual acuity provided to the presbyopic subject by eithermultifocal contact lens of the pair, alone. In addition, in certainembodiments of the batches of the present invention, the multifocalcontact lenses are near-center aspheric multifocal contact lenses. Themultifocal contact lenses can include a toric optic zone having acylinder power that is effective in correcting astigmatism of thepresbyopic subject (e.g., have any cylinder power from about −0.75 D toabout −2.75 D). The multifocal contact lenses of the batches can behydrogel or silicone hydrogel contact lenses, as described herein.

The present invention also provides methods of manufacturing batches ofmultifocal contact lenses.

A method of manufacturing a batch of multifocal contact lenses includesa step of forming a plurality of multifocal contact lenses from apolymerizable composition. As discussed herein, the lenses can be formedby forming polymer buttons and lathing an aspheric power profile onto asurface of the polymer button. Or, the lenses can be static cast moldedfrom molds that have an aspheric power profile provided by a contactlens mold that is formed using a metallic insert with an aspheric powerprofiled machined thereon. As discussed herein, each of the multifocalcontact lenses includes an optic zone having an optic zone center and anoptic zone perimeter spaced radially away from the optic zone center.The optic zone perimeter defines a boundary between the optic zone and aperipheral zone. The optic zone has an aspheric power profile extendingfrom the optic zone center towards the optic zone perimeter andproviding a near vision refractive power and a distance visionrefractive power such that each of said multifocal contact lenses has anAdd power, wherein the Add power is the absolute difference in powerbetween the near vision refractive power and the distance visionrefractive power.

As described in the context of the batches of the present invention, andrepeated here for clarity, the plurality of multifocal contact lensesincludes a plurality of first multifocal contact lens groups. Each firstmultifocal contact lens group includes multifocal contact lensesproviding a unique single distance vision refractive power for the firstmultifocal contact lens group (such as a group as illustrated in FIG.10A). The aspheric power profile of each of the multifocal contactlenses within a single contact lens group provides a single Add powerselected from a value from about 0.75 diopters to 2.00 diopters over aradial distance of 2.5 mm from the optic zone center for each lens ofthe series, and the Add power provided by the aspheric power profile ofindividual multifocal contact lenses of any of the first multifocalcontact lens groups varies by no more than ±0.25 diopters compared tothe Add power provided by a relative aspheric power profile of theplurality of multifocal contact lenses. The relative aspheric powerprofile being the average of power profiles of the plurality ofmultifocal contact lenses and in which the distance vision refractivepower at a radial distance of 2.5 mm is fixed at 0.00 diopters. Inaddition, the aspheric power profile of the individual multifocalcontact lenses of any of the first multifocal contact lens groupsdiffers by no more than ±0.375 diopters compared to the relativeaspheric power profile of the plurality of multifocal contact lensesalong the power profile for each radial distance measured along thepower profile.

In some methods, another step is provided, and is a step of forming aplurality of second multifocal contact lens groups, which as describedabove, have different power profiles than the power profiles of thefirst multifocal contact lens groups. Each of the second multifocalcontact lens groups includes multifocal contact lenses providing aunique single distance vision refractive power for the second multifocalcontact lens group, and each of said multifocal contact lenses of thesecond multifocal contact lens groups has an aspheric power profile thatprovides an AUC that is between 5% to 45% greater than an AUC of therelative aspheric power profile of the multifocal contact lenses of thefirst multifocal contact lens groups.

In the methods of the invention, the forming may include a step ofdesigning the multifocal contact lenses to have an aspheric powerprofile in which the aspheric power profile of individual multifocalcontact lenses of the plurality of multifocal contact lenses has amaximum rate of power change having an absolute value greater than 0.0D/mm and less than 0.9 D/mm.

The methods may also include a step of providing the plurality ofmultifocal contact lenses as lens pairs that are effective to provide animproved visual acuity to a presbyopic patient compared to the visualacuity provided to the presbyopic patient by either multifocal contactlens of the pair, alone.

In the methods, the forming may include a step of polymerizing thepolymerizable composition in contact lens mold assemblies having acontact lens shaped cavity in each assembly, and as illustrated in FIG.9. Additionally, the method may include a step of shaping a contact lensmold member insert to provide the optic zone of the plurality ofmultifocal contact lenses, and forming a first contact lens mold memberusing the contact lens mold member insert, and placing the first contactlens mold member in contact with a second contact lens mold member toform a contact lens mold assembly, also as illustrated in FIG. 9. Or, inthe present methods, the forming step may comprise polymerizing thepolymerizable composition in a mold to form a polymerized composition,and machining the polymerized composition into a multifocal contact lensof the batch.

Any of the present manufacturing methods may further include a step ofpackaging individual multifocal contact lenses into primary contact lenspackages, and placing a single group of packaged multifocal contactlenses, of either the first group or the second group, into a secondarypackage, in which the secondary package includes indicia identifying thesingle distance refractive power of the multifocal contact lens group,and optionally, the Add power of the multifocal contact lenses of thegroup.

Aspects of the present invention also relate to sets of multifocalcontact lenses and related methods. One example of a set used in thecontext of the present invention is a fitting set, as understood bypersons of ordinary skill in the art. Fitting sets are provided to ECPssuch that the ECP can fit subjects with different contact lenses todetermine which contact lenses provide an acceptable amount of visionimprovement and comfort, as discussed herein. The present sets ofmultifocal contact lenses in accordance with the present inventioninclude series of multifocal contact lenses, such as a series ofmultifocal contact lenses for the dominant eye of a presbyopic subjectand a series of multifocal contact lenses for the non-dominant eye ofthe presbyopic subject. The two series can be present as distinct units,such as two separate series of lenses, or can be provided as a singleunit, where all of the multifocal contact lenses are present in a singlesystem, but the dominant eye series and the non-dominant eye seriesbecome more defined upon selection of two lenses for the presbyopicsubject.

Thus, in accordance with the present disclosure, a set of the inventionis now described. A set of multifocal contact lenses for improvingvision of presbyopic subjects includes a dominant eye series and anon-dominant eye series. When the set is a fitting set, as understood bypersons of ordinary skill in the art, the set can be understood to be adevice or article of manufacture in which the first multifocal contactlenses and the second multifocal contact lenses are packaged together inthe device to provide to an ECP. The ECP can select a first multifocalcontact lens and a second multifocal contact lens, based on theteachings of the present disclosure, and use such multifocal contactlenses in a fitting procedure for the presbyopic subject.

As described herein, each of the multifocal contact lenses in eachseries includes an optic zone that has an optic zone center and an opticzone perimeter spaced radially away from the optic zone center. Theoptic zone perimeter defines a boundary between the optic zone and theperipheral zone of the contact lens. The optic zone has an asphericpower profile extending from the optic zone center towards the opticzone perimeter and provides a near vision refractive power and adistance vision refractive power such that each of said multifocalcontact lenses has an Add power. The Add power is the absolutedifference in power between the near vision refractive power and thedistance vision refractive power, as described herein.

In the sets of the present invention, the dominant eye series includes aplurality of dominant eye patient lens sets (e.g., two or more dominanteye patient lens sets). The dominant eye patient lens sets correlate tothe Add power requirements of presbyopic subjects, such as medium Add,high Add, and low Add. The dominant eye series can include dominant eyepatient lens sets, such as medium and high Add sets, low and medium Addsets, low and high Add sets, or low, medium, and high Add sets. Oneexample is illustrated in FIG. 8, as described further herein.

The plurality of dominant eye patient lens sets includes a firstdominant eye patient lens set, such as a medium Add set. The firstdominant eye patient lens set includes multifocal contact lens groupsthat include multifocal contact lenses providing unique distance visionrefractive powers, as described herein for the batches of the presentinvention. Each contact lens group includes at least one multifocalcontact lens. Since each group has a unique distance vision refractivepower, the first dominant eye patient lens set can be understood toinclude a plurality of multifocal contact lenses having distance visionrefractive powers from +20.00 D to −20.00 D, or any value therebetween.In some embodiments, the multifocal contact lenses of the first dominanteye patient lens set can have distance vision refractive powers from−10.00 D to +6.00 D in various increments, such as 0.25 D increments.Subsets of those ranges of distance vision refractive powers are alsoincluded in the scope of the present sets of multifocal contact lenses.Thus, for a medium Add patient lens set of the dominant eye series, themultifocal contact lenses of the medium Add patient lens set can beprovided in a range of distance powers from +20.00 D to −20.00 D, as oneexample, from −10.00 D to +6.00 D. Similar ranges can be provided forthe high Add patient lens sets, and the low Add patient lens sets.

The aspheric power profile of each of the multifocal contact lenses ofthe first dominant eye patient lens set provides a single Add powerselected from a value from about 0.75 D to 2.00 D over a radial distanceof 2.5 mm from the optic zone center for each lens of the series. Thisshape of the aspheric power profile can be understood with thedescription and drawings of FIGS. 1A-1F, and 10B-10D, and 11B. In someembodiments, the Add power is a value from 1.00 D to 1.90 D. Forexample, the Add power may be about 1.00 D, 1.10 D, 1.20 D, 1.25 D, 1.30D, 1.40 D, 1.50 D. 1.60 D. 1.70 D. 1.75 D, 1.80 D, or 1.90 D, or anyvalue therebetween. As another example, in some embodiments of thepresent sets, the Add power is a value in a range from 0.75 D to 1.75 D.

The Add power provided by the aspheric power profile of the individualmultifocal contact lenses of the first dominant eye patient lens setvaries by no more than ±0.25 D, as compared to the Add power provided bythe relative aspheric power profile of the multifocal contact lenses ofthe first dominant eye patient lens set. Similar to that describedherein, the relative aspheric power profile corresponds to the averageof power profiles of a plurality of multifocal contact lenses of thefirst dominant eye patient lens set, in which the distance visionrefractive power at a radial distance of 2.5 mm is fixed at 0.00 D.

The non-dominant eye series of the sets of the present invention alsoincludes a plurality of patient lens sets. More specifically, thenon-dominant eye series includes a plurality of non-dominant eye patientlens sets correlating to the Add power requirements of presbyopicsubjects, such as medium Add, high Add, and low Add, as described abovefor the dominant eye patient lens sets. The plurality of non-dominanteye patient lens sets includes a first non-dominant eye patient lens setthat includes multifocal contact lenses. The multifocal contact lensesof the first non-dominant eye patient lens set each have an asphericpower profile that provides a single Add power selected from a valuefrom about 0.75 D to 2.00 D over a radial distance of 2.5 mm from theoptic zone center. The Add power of these lenses is similar or the sameas those for the dominant eye patient lens sets. However, the distancevision refractive power provided by the aspheric power profile of themultifocal contact lenses of the first non-dominant eye patient lens setis offset by about +0.25 D to about +1.25 D relative to the distancepower correction for the presbyopic subject.

The set of the present invention may also include a second non-dominanteye patient lens set as a component of the non-dominant eye series. Insuch an embodiment, each of the multifocal contact lenses of the secondnon-dominant eye patient lens set has an aspheric power profile thatprovides an AUC that is between 5% to 45% greater than the AUC of therelative aspheric power profile of the multifocal contact lenses of thefirst non-dominant eye patient lens set. In some embodiments, the AUC isless than 35% greater, and in some further embodiments, the AUC of theaspheric power profile of the lenses of the second non-dominant eyepatient lens set is less than 30% greater than the relative asphericpower profile. One example of such an aspheric power profile of thesecond non-dominant eye patient lens sets is illustrated at Lens C inFIG. 11B.

In the sets that include a second non-dominant eye patient lens set, theaspheric power profile of each of the multifocal contact lenses of thesecond non-dominant eye patient lens set provides a single Add power ofno greater than 2.00 diopters over a radial distance of 2.5 mm from theoptic zone center for each lens of the second non-dominant eye patientlens set, and the aspheric power profile of the multifocal contactlenses of the second non-dominant eye patient lens set is offset byabout +0.25 diopters to about +1.25 diopters relative to the distancepower correction for the presbyopic subject.

In any of the sets of the present invention, the relative asphericalpower profile of the multifocal contact lenses of the dominant eyeseries and the relative aspherical power profile of the multifocalcontact lenses of the non-dominant eye series differ by less than ±0.375D compared to each other along the power profile for every radialdistance measured along the power profile.

The non-dominant eye series of any of the preceding sets may alsoinclude a third non-dominant eye patient lens set, such as a low Addpatient lens set, that includes multifocal contact lenses. Each of themultifocal contact lenses of the third non-dominant eye patient lens sethave an average aspheric power profile that differs by less than ±0.375D compared to the average aspheric power profile of the multifocalcontact lenses of the first dominant eye patient lens set along thepower profile for every radial distance measured along the powerprofile.

In any of the preceding sets of multifocal contact lenses, the asphericpower profile of the multifocal contact lenses of the non-dominant eyeseries has a maximum rate of power change greater than 0.00 D/mm andless than 1.00 D/mm. For example, the maximum rate of power change maybe less than 0.95 D/mm. In some embodiments, the maximum rate of powerchange may be represented by an absolute value that is from about 0.7D/mm to about 0.8 D/mm. In some embodiments, the maximum rate of powerchange occurs at a radial distance from about 2.0 mm to about 2.5 mm.These embodiments may be useful for the medium Add patient lens sets andthe low Add patient lens sets. In some embodiments, the maximum rate ofpower change may be represented by an absolute value that is from about0.7 D/mm to about 0.9 D/mm, and it may be present at a radial distancefrom about 0.8 mm to about 2.2 mm. These embodiments may be useful forthe high Add patient lens set, if so desired.

In any of the preceding sets, the multifocal contact lenses of thedominant eye series and the multifocal contact lenses of thenon-dominant eye series can be grouped in lens pair sets. The lens pairsets include a first patient lens pair set, such as for medium Addpresbyopes, a second patient lens pair set, such as for high Addpresbyopes, and a third patient lens pair set, such as for low Addpresbyopes, such that any pair of multifocal contact lenses of the lenspair sets is effective to provide an improved visual acuity to apresbyopic subject compared to the visual acuity provided to thepresbyopic subject by either multifocal contact lens of the pair, alone.

As described herein, in any of the present lens sets, the multifocalcontact lenses can be near-center asphere lenses, can include a toricoptic zone for correcting astigmatism, or can be hydrogel or siliconehydrogel contact lenses, or combinations thereof.

In some embodiments of the sets of the present invention, the multifocalcontact lenses of the dominant eye series and the multifocal contactlenses of the non-dominant eye series are grouped in lens pair sets,including a medium Add lens pair set, and a low Add lens pair set, and ahigh Add lens pair set. The high Add lens pair set includes a) a firstmultifocal contact lens providing an Add power correction from about1.50 D to 2.00 D and has an aspheric power profile effective to improvevisual acuity of a dominant eye of a presbyopic subject, and b) a secondmultifocal contact lens providing an Add power correction from about1.50 D to 2.00 D and having an aspheric power profile in which thedistance vision power correction is offset by about +0.25 D to about+1.25 D relative to the distance power correction for the presbyopicsubject.

In some embodiments of the present lens sets, multifocal contact lensesof the dominant eye series and the multifocal contact lenses of thenon-dominant eye series are grouped in lens pair sets, including amedium Add lens pair set, and a low Add lens pair set, and a high Addlens pair set, said high Add lens pair set including two multifocalcontact lenses, at least one of the two multifocal contact lensesproviding an Add power correction greater than 2.00 diopters.

One example of a set in accordance with the present invention isillustrated in FIG. 8. In this example, the set may be understood to bea fitting set. A set 30 includes a dominant eye series 32 and anon-dominant eye series 34. The dominant eye series 32 includes aplurality of dominant eye patient lens sets 32A, 32B, and 32C. Thenon-dominant eye series includes a plurality of non-dominant eye patientlens sets 34A, 34B, and 34C. The patient lens sets each correspond tothe Add power requirements of presbyopic subjects. For example, thepatient lens sets 32A and 34A correspond to the low Add presbyopes; thepatient lens sets 32B and 34B correspond to the medium Add presbyopes;and the patient lens sets 32C and 34C correspond to the high Addpresbyopes. As illustrated in this set 30, each of the lenses share acommon single aspheric power profile, represented by the label Lens A,as described herein. For the patient lens set 34B, for medium Addsubjects, the non-dominant eye is over corrected by +0.25 D to +1.25 D,and preferably is over corrected by +0.75 D. For the patient lens set34C, for high Add subjects, the non-dominant eye is over corrected by+0.25 D to +1.25 D, and preferably is over corrected by +0.75 D or +1.00D.

Another example of a lens set in accordance with the present inventionis illustrated in FIG. 13. This lens set 130 is identical to the lensset 30 of FIG. 8, except that for the non-dominant eye series patientlens set for high Add presbyopes, the lenses of this patient lens set134C have a different aspheric power profile, as represented by thelabel Lens C, which can be in reference to the Lens C power profile inFIG. 11B. Although the power profile of Lens C provides a greater AUCthan the Lens A power profile, it is still over corrected for distancevision from about +0.25 D to about +1.25 D, and preferably, the overcorrection is +0.75 D or +1.00 D.

As described herein, in addition to the monocular differences in visualacuity, and the improvement in binocular visual acuity, the presentmultifocal contact lenses are manufactured with reduced variabilitywithin batches of lenses and across ranges of distance powers of lenses.For example, unlike some multifocal contact lenses that vary the Addpower as the distance power of the lens in a lens set changes, thepresent multifocal contact lenses maintain a substantially constant Addpower across different distance powers of the lenses. In addition, inthe present lens sets, less than three Add powers are required within aseries of lenses, unlike some other existing multifocal contact lenses.Further, the variability in power profile shape is reduced among lensesof different distance powers unlike existing multifocal contact lenses.

In accordance with the present teachings and present lens sets, theinvention also relates to methods of providing multifocal contact lensesfor improving vision of presbyopic subjects. Such methods include a stepof manufacturing a plurality of multifocal contact lenses, as hereindescribed. Preferably, the multifocal contact lenses are manufacturedusing a static cast molding process, as illustrated by way of example inFIG. 9. Each of the multifocal contact lenses includes an optic zonehaving an optic zone center and an optic zone perimeter spaced radiallyaway from the optic zone center. The optic zone perimeter defines aboundary between the optic zone and a peripheral zone of the contactlens. The optic zone has an aspheric power profile extending from theoptic zone center towards the optic zone perimeter and provides a nearvision refractive power and a distance vision refractive power such thateach of said multifocal contact lenses has an Add power, wherein the Addpower is the absolute difference in power between the near visionrefractive power and the distance vision refractive power. The methodfurther includes a step of packaging the multifocal contact lenses incontact lens packages to produce packaged multifocal contact lenses. Thecontact lens packages can include primary packaging, such as blisterpacks or vials, secondary packaging, such as cartons, containing one ormore primary packages of contact lenses, or tertiary packaging, such asboxes, containing one or more secondary packages.

The packaged multifocal contact lenses are provided to a contact lensdistributor, a contact lens retailer, or an ECP, or combinationsthereof. The packaged contact lenses include a dominant eye series ofmultifocal contact lenses and a non-dominant eye series of multifocalcontact lenses.

The dominant eye series includes a plurality of dominant eye patientlens sets correlating to Add power requirements of presbyopic subjects,as described above. The plurality of patient lens sets includes a firstdominant eye patient lens set that includes multifocal contact lensgroups that include multifocal contact lenses providing unique distancevision refractive powers. Each group includes at least one multifocalcontact lens, and the aspheric power profile of each of the multifocalcontact lenses of the first dominant eye patient lens set provides asingle Add power selected from a value from about 0.75 diopters to 2.00diopters over a radial distance of 2.5 mm from the optic zone center foreach lens of the series. The Add power provided by the aspheric powerprofile of individual multifocal contact lenses of the first dominanteye patient lens set varies by no more than ±0.25 D compared to the Addpower provided by a relative aspheric power profile of the multifocalcontact lenses of the first dominant eye patient lens set. Where, asdescribed herein, the relative aspheric power profile corresponds to theaverage of power profiles of a plurality of multifocal contact lenses ofthe first dominant eye patient lens set and in which the distance visionrefractive power at a radial distance of 2.5 mm is fixed at 0.00 D.

The non-dominant eye series of the present methods includes a pluralityof patient lens sets correlating to Add power requirements of presbyopicsubjects, as described herein. The plurality of patient lens setsincludes a first non-dominant eye patient lens set that includesmultifocal contact lenses, each of the multifocal contact lenses of thefirst non-dominant eye patient lens set have an aspheric power profilethat provides a single Add power selected from a value from about 0.75diopters to 2.00 diopters over a radial distance of 2.5 mm from theoptic zone center for each lens of the first non-dominant eye patientlens set, and the distance vision refractive power provided by theaspheric power profile of the multifocal contact lenses of the firstnon-dominant eye patient lens set is offset by about +0.25 diopters toabout +1.25 diopters relative to the distance power correction for apresbyopic subject.

In some embodiments of the present methods, the non-dominant eye seriesof the provided packaged contact lenses includes a second non-dominanteye patient lens set that includes multifocal contact lenses. Each ofthe multifocal contact lenses of the second non-dominant eye patientlens set have an aspheric power profile that provides an AUC that isbetween 5% to 45% greater than an AUC of the relative aspheric powerprofile of the multifocal contact lenses of the first non-dominant eyepatient lens set, as described hereinabove.

In the foregoing method, the aspheric power profile of each of themultifocal contact lenses of the second non-dominant eye patient lensset can provide a single Add power of no greater than 2.00 D over aradial distance of 2.5 mm from the optic zone center for each lens ofthe second non-dominant eye patient lens set, and the aspheric powerprofile of the multifocal contact lenses of the second non-dominant eyepatient lens set is offset by about +0.25 D to about +1.25 D relative tothe distance power correction for the presbyopic subject.

In any of the preceding methods, the relative aspherical power profileof the multifocal contact lenses of the dominant eye series and therelative aspherical power profile of the multifocal contact lenses ofthe non-dominant eye series can differ by less than ±0.375 D compared toeach other along the power profile for every radial distance measuredalong the power profile.

In any of the preceding methods, the non-dominant eye series can includea third non-dominant eye patient lens set that includes multifocalcontact lenses, wherein each of the multifocal contact lenses of thethird non-dominant eye patient lens set have an average aspheric powerprofile that differs by less than ±0.375 D compared to the averageaspheric power profile of the multifocal contact lenses of the firstdominant eye patient lens set along the power profile for every radialdistance measured along the power profile.

As discussed herein, in certain embodiments the aspheric power profileof the multifocal contact lenses of the non-dominant eye series has anabsolute maximum rate of power change less than 1.0 D/mm, for examplefrom 0.7 to 0.9 D/mm. As a further example, the aspheric power profilemay have an absolute value from about 0.7 diopters/mm to about 0.8diopters/mm at a radial distance of about 2.0 mm to about 2.5 mm.

In some methods, the multifocal contact lenses of the dominant eyeseries and the multifocal contact lenses of the non-dominant eye seriesare grouped in lens pair sets, including a first patient lens pair set,a second patient lens pair set, and a third patient lens pair set, suchthat any pair of multifocal contact lenses of the lens pair sets iseffective to provide an improved visual acuity to a presbyopic subjectcompared to the visual acuity provided to the presbyopic subject byeither multifocal contact lens of the pair, alone.

The present invention also provides additional methods of using themultifocal contact lenses. For example, such methods can be understoodto relate to the perspective of an ECP or other similar person or entityresponsible for eye examinations and prescribing contact lenses. Suchmethods do not involve a step of treating a presbyopic subject since themultifocal contact lenses are self-administered by the subject toprovide temporary vision correction or vision improvement (i.e., visioncorrection when the subject is wearing the multifocal contact lenses).The subject's vision remains uncorrected when the subject removes themultifocal contact lenses.

A method of prescribing multifocal contact lenses to a presbyopicsubject as provided by the present invention, and as understood from thedisclosure herein, includes a step of fitting the presbyopic subjectwith a pair of multifocal contact lenses. The presbyopic subject is amedium Add or high subject, or stated differently, the presbyopicsubject requires an Add power correction of at least 1.25 D, such asfrom 1.25 D to 3.00 D. Thus, the presbyopic subject requires an Addpower correction of one of 1.25 D, 1.50 D, 1.75 D, 2.00 D, 2.25 D, 2.50D, 2.75 D, or 3.00 D. Many presbyopes require an Add power correction inaccordance with these methods from 1.25 D to 2.50 D.

Of the pair of multifocal contact lenses so fit, a first multifocalcontact lens includes an aspheric power profile derived from a firstnominal, or target, aspheric power profile, and the second multifocalcontact lens of the pair comprises a second aspheric power profilederived from the first nominal aspheric power profile. Although theaspheric power profiles of the first and second multifocal contactlenses are derived from a single nominal aspheric power profile, theaspheric power profile of the second multifocal contact lens provides adistance vision refractive power offset by about +0.25 D to about +1.25D relative to the distance power correction for the non-dominant eye ofthe presbyopic subject. Thus, the monocular distance visual acuity isdifferent for each eye with each contact lens (e.g., the dominant eye isfully corrected for distance vision, and the non-dominant eye isover-corrected for distance vision), and binocular summation is stillmaintained.

The aspheric power profiles of the first and second multifocal contactlenses are substantially similar, as described above with respect toFIGS. 10A-10D. It can be understood in general terms that the first andsecond multifocal contact lenses, which may or may not have differentdistance vision refractive powers (depending on the distance visioncorrection needed by the subject in each eye), have aspheric powerprofiles that are derived from a single nominal or target aspheric powerprofile used in the design of the multifocal contact lenses. Inaddition, although they are derived from a single nominal aspheric powerprofile, the aspheric power profiles of the first and second multifocalcontact lenses may vary slightly due to manufacturing tolerances andinspection techniques, as described herein. However, unlike existingmultifocal contact lenses, the present multifocal contact lenses havesubstantially similar aspheric power profiles across the range ofdistance vision refractive powers (e.g., −20.00 D to +20.00 D; or −10.00D to +6.00 D; or −6.00 D to 0.00 D, etc.) and for presbyopic subjectsrequiring different amounts of Add power correction. In comparison, someexisting multifocal contact lenses have a first aspheric power profilewith a relatively low amount of Add power for low Add presbyopes (e.g.,presbyopes requiring an Add power correction from 0.25 D to 1.00 D), asecond aspheric power profile with a modest amount of Add power formedium Add presbyopes (e.g., presbyopes requiring an Add powercorrection from 1.25 D to 1.75D), and a third aspheric power profilewith a large amount of Add power for high Add presbyopes (e.g.,presbyopes requiring an Add power correction of at least 2.00 D). Thus,with the present multifocal contact lenses, the fitting process issimpler than existing fitting processes for existing multifocal contactlenses. In some methods, it can be understood that with the presentmultifocal contact lenses and sets of multifocal contact lenses, lessthan three different patient lens sets are provided for low, medium, andhigh Add presbyopic subjects. This is because the multifocal contactlenses have similar lens designs or aspheric power profiles, unlike someexisting multifocal contact lenses that have three different designs orpower profiles for the three different groups of prebyopes. An exampleof this simplified fitting system is illustrated in FIG. 8, as describedherein. As can be understood from the drawings, a single lens design(Lens A) having a power profile as illustrated in FIGS. 10B and 10C canbe fit in accordance with the present invention for each eye of low,medium, and high Add presbyopes.

During the fitting process, an ECP can evaluate the vision provided withthe individual multifocal contact lenses and the pair of multifocalcontact lenses, as well as the comfort and fitting characteristics ofthe multifocal contact lenses. If the vision provided by the contactlenses is acceptable to the presbyopic subject, and the comfort and thefit is acceptable, the ECP can issue a prescription for the presentmultifocal contact lenses. As understood in the art, the fitting processcan include steps of recording corneal diameter, determining thedistance power correction, near power correction, intermediate powercorrection, cylinder power correction and prismatic power correctionnecessary to correct the subject's vision, observing the centration ofthe lens(es), or observing the movement of the lens(es), or anycombination thereof, in addition to others.

In the present methods, some methods may optionally include a secondstep of fitting a pair of multifocal contact lenses to the presbyopicsubject. For example, a method may include a step of fitting a secondpair of multifocal contact lenses, where the second pair of multifocalcontact lenses includes a first multifocal contact lens have the sameaspheric power profile as the first aspheric power profile of the firstmultifocal contact lens of the first pair, and the second contact lensof the second pair has an aspheric power profile that provides an AUCthat is between 5% to 45% greater than the AUC of the aspheric powerprofile of the first multifocal contact lens of the second pair.

The foregoing embodiment of the methods can be understood with referenceto FIG. 11B and FIG. 13. For example, if the presbyope is not satisfiedwith the fitting characteristics of the first multifocal lens pair, thepresbyope can be fit with a second multifocal contact lens pair, such asa pair consisting of a first multifocal contact lens having a anaspheric power profile as represented by Lens A in FIG. 11B, and asecond multifocal contact lens having an aspheric power profilerepresented by Lens C in FIG. 11B. This may be particularly useful inhigh Add presbyopes, as reflected in the exemplary fitting set depictedin FIG. 13.

As illustrated in FIG. 13, if the presbyopic subject is fit with asecond pair of multifocal contact lenses in accordance with the presentinvention, the aspheric power profile of the second multifocal contactlens of the second pair is labeled to provide a distance visionrefractive power that is offset by about +0.25 D to about +1.25 Drelative to the distance power correction for the non-dominant eye ofthe presbyopic subject, which is similar in principle to the secondmultifocal contact lens of the first pair.

In addition, some of the present methods may further include a step ofconducting an eye examination of the presbyopic subject to determinewhich eye of the presbyopic subject is the dominant eye. As discussedhereinabove, ocular dominance can be determined using any conventionaltechnique, including the lens fogging technique.

The methods may also include a step of determining the prescription ofthe presbyopic subject and prescribing the first and second multifocalcontact lenses to the presbyopic subject. The first and secondmultifocal contact lenses can be from either the first lens pair or thesecond lens pair described herein.

As can be understood from the present disclosure, the first and secondmultifocal contact lenses may be near-center aspheres, one or both mayinclude a toric optic zone effective in correcting astigmatism of thepresbyopic subject, or may be either hydrogel contact lenses or siliconehydrogel contact lenses, or combinations thereof.

Some of the present methods may also include a step of providing themultifocal contact lenses to the presbyopic subject for selfadministration by the subject. As explained above, the present methodsare not methods of medical treatment, and thus, in some contexts, thestep of administration by the presbyopic subject may is not claimed or asubject of the present invention. Some further methods may include astep of obtaining data from the subject to determine the prescription ofthe presbyopic subject.

In addition to the foregoing, some embodiments of the present multifocalcontact lenses can have aspheric power profiles that are free of atransition zone within the optic zone. This is possible due to therelatively slow rate of change of diopters/mm over a radial distance of2.5 mm, as compared to multifocal contact lenses with greater rates ofchange. However, although these embodiments do not have transition zonesin the optic zone, transitions or blends may be provided at junctions,such as at a junction between the optic zone perimeter and theperipheral zone, or a junction between the peripheral zone and the edgeregion of the contact lenses, or combinations thereof.

EXAMPLES

The following Examples illustrate certain aspects and advantages of thepresent invention, which should be understood not to be limited thereby.

Example 1 Multifocal Contact Lens Manufacture

Multifocal contact lenses having an aspheric power profile, as describedhereinabove, and as illustrated in FIGS. 1A-1F are produced using astatic cast molding process.

Metal inserts are machined to form optical quality surfacescorresponding to the surfaces of the multifocal contact lenses. Anominal or target or pre-determined aspheric power profile is used toform an aspheric power profile within the optic zone portion of theoptical quality surface of the inserts. An example of a nominal asphericpower profile is illustrated in FIGS. 1C-1F.

The inserts are placed in an injection molding machine to form contactlens mold cavities when inserts are placed near each other. Contact lensmold material, such as pellets of polystyrene, polypropylene, vinylalcohol polymers, and the like, are melted and injected into the contactlens mold cavities to form female contact lens mold members and malecontact lens mold members. The female contact lens mold member has aconcave optical quality surface corresponding to the anterior surface ofa contact lens. The male contact lens mold member has a convex opticalquality surface corresponding to the posterior surface of a contactlens.

A volume of a polymerizable lens forming composition is placed incontact with the concave surface of a female mold member. A male moldmember is placed in contact with the female mold member to form acontact lens mold assembly comprising a contact lens shaped cavitycontaining the polymerizable lens forming composition. Multifocalcontact lenses are produced from polymerizable lens forming compositionshaving a U.S. Adopted Name (USAN) of omafilcon A, or comfilcon A,enfilcon A, or stenfilcon A. The resulting multifocal contact lenses arehydrogel contact lenses or silicone hydrogel contact lenses.

Contact lens mold assemblies are placed in thermal ovens or ultravioletovens to allow the polymerizable compositions to polymerize by heat orultraviolet radiation, respectively. The contact lens molds are exposedto curing conditions for about 1 hour or more.

After polymerizing the precursor compositions, the contact lens moldassemblies are demolded to separate the male and female mold members.The polymerized contact lens product is delensed from one of the moldmembers by immersing the lens and mold member in a delensing liquid, ormechanically, such as by compressing the mold member to release thecontact lens product.

The delensed lens product is then either placed in a contact lenspackage, such as in a cavity of a blister pack which is then filled witha contact lens packaging solution, or is optionally washed with water,alcohol, or combinations thereof, prior to placement in the contact lenspackage. The contact lens packages, each containing a single multifocalcontact lens, is then sealed, and sterilized by autoclaving. Thesterilized packages are placed in secondary packaging, such as cartons.The secondary packaging is then placed in tertiary packaging, such asboxes. The contact lens packages are also placed in display devicescontaining contact lens storage areas. Such display devices with thecontact lenses can be understood to be fitting sets.

The multifocal contact lenses are manufactured with different distancevision refractive powers or distance powers. The distance visionrefractive powers range from −20.00 D to +20.00 D. The multifocalcontact lenses are manufactured in batches, each batch having adifferent distance vision refractive power. For example, batches aremanufactured having distance vision refractive powers from −20.00 D to−10.00 D in 1 D increments; from −10.00 D to +6.00 D in 0.25 Dincrements, and from +6.00 D to +20.00 D in 1 D increments.

Example 2 Visual Acuity—Medium Add Subjects

A group of presbyopic subjects who require an Add power correction of+1.25 D to +1.75 D, as determined by an eye care practitioner (ECP; thesubjects have Add power prescriptions of either +1.25 D, +1.50 D, or+1.75 D), are selected for fitting with the present multifocal contactlenses, as described hereinabove and illustrated in FIGS. 1A-1F. Themultifocal contact lenses so fit have an Add power from about 1.00 D toless than 1.25 D, for example, about 1.15 D, over the central 5 mmdiameter of the optic zone (2.5 mm radial distance).

The ECP determines ocular dominance, distance vision refractive powercorrection, and Add power requirements for each of the subjects. Thedominant eye is optimally or fully corrected for distance vision with afirst multifocal contact lens of the present invention (e.g., thedistance vision refractive power of the first multifocal contact lenscorresponds to the distance vision prescription of the dominant eye, asdetermined by the ECP). That is, a first multifocal contact lens havinga −3.00 D distance vision refractive power is provided for the subject'sdominant eye if the eye requires about −3.00 D vision correction toachieve acceptable monocular visual acuity (such as, 20/30 or betterusing Snellen notation). A second multifocal contact lens of the presentinvention is selected for the non-dominant eye such that the distancevision refractive power of the multifocal contact lens is over-correctedrelative the distance vision prescription of the non-dominant eye. Theover-correction is from about +0.25 D to about +1.25 D; for example, theover-correction can be +0.25 D, +0.50 D, +0.75 D, +1.00 D, or +1.25 D.In this Example, the over-correction is +0.75 D. Therefore, if a subjectrequires a −2.00 D distance vision correction for the non-dominant eye,the subject is fit with the second multifocal contact lens having adistance vision refractive power of −1.25 D. With this second multifocalcontact lens, which has an Add power less than 1.25 D, the subjectsachieve acceptable monocular near vision correction (such as, 20/30 orbetter using Snellen notation). These first and second multifocalcontact lenses are illustrated as Lens A in FIGS. 2A and 2B.

The same group of subjects is fit with a pair of multifocal contactlenses having a greater Add power and a greater rate of power change(1st order derivative) compared to the pair described in the precedingtwo paragraphs. The two lenses of this pair of multifocal contact lensesare illustrated as Lens B in FIGS. 2A and 2B. As shown in FIG. 2B, andas described above, Lens B has greater Add power than Lens A, has agreater rate of power change than Lens A, and correspondingly, has agreater area under the curve (AUC) than Lens A, as depicted by theshaded areas of the power profiles in FIGS. 2A and 2B.

Visual acuity is determined with high illumination and high contrast forsubjects wearing a pair of the Lens A lenses, and then the highillumination, high contrast visual acuity is determined for the subjectswearing a pair of the Lens B lenses. The visual acuity is determined atdistant or far viewing distances (e.g., at least 6 meters), at nearviewing distances (e.g., at 60 centimeters or less), and at intermediateviewing distances (e.g., at a distance between 60 centimeters and 1.5meters). Visual acuity results are illustrated in FIG. 3 and the dataare represented as logMAR values. 20/20 visual acuity is reflected as0.00 on the logMAR chart, and better visual acuity is represented byrelatively more negative logMAR values.

As shown in FIG. 3, pairs of Lens A lenses (e.g., multifocal contactlenses in accordance with the present invention) provide improved visualacuity compared to Lens B lenses at distant and intermediate viewingdistances (that is, the Lens A logMAR values are more negative than LensB logMAR values). At near viewing distances, the Lens A logMAR valuesare slightly more positive than the Lens B logMAR values, but thedifference is not statistically significant.

Visual acuity is also determined with low illumination and low contrastfor the subjects for Lens A lenses and Lens B lenses at distant and nearviewing distances (see FIG. 4). Although both logMAR values are greaterthan zero, the Lens A lenses provided improved distant visual acuity atlow illumination and low contrast (more negative logMAR value), andequal near visual acuity at low illumination and low contrast, comparedto Lens B lenses.

Visual acuity measurements were actually conducted as set forth above inthis Example 2 and the results actually obtained were as predictedabove.

Thus, the Lens A lenses, which are corrected for distance vision in thedominant eye, and over-corrected for distance vision in the non-dominanteye, and are binocularly under-corrected for the Add power requirementof the subjects (without including the over-correction of thenon-dominant eye, as described herein), provide clinically acceptablenear visual acuity without compromising distance and intermediate visualacuity compared to Lens B lenses, which have an Add power that moreclosely corresponds to the Add power requirements of the present mediumAdd subjects.

Example 3 Visual Acuity—High Add Subjects

A group of presbyopic subjects who require an Add power correction of+2.00 D or more, as determined by an eye care practitioner (ECP; thesubjects have Add power prescriptions of either +2.00 D, +2.25 D, +2.50D, +2.75 D, or +3.00 D) are selected for fitting with the presentmultifocal contact lenses, as described hereinabove and illustrated inFIGS. 1A-1F. The multifocal contact lenses so fit have an Add power fromabout 1.00 D to less than 1.25 D, for example, about 1.15 D, over thecentral 5 mm diameter of the optic zone. These lenses are the samedesign, or same power profile, as the Lens A lenses described in Example2.

This high Add group of subjects is fit for Lens A lenses or Lens Blenses, as described in Example 2. The primary difference betweenExample 2 and Example 3 is that the subjects of Example 3 require higherAdd power correction, as determined by the ECP.

Similar to the results described in Example 2, high Add subjects wearinga pair of Lens A lenses (i.e., optimally or best corrected for distancevision in the dominant eye, and over-corrected for distance vision inthe non-dominant eye by +0.75 D) exhibit improved visual acuity fordistant viewing distances under high illumination, high contrast, andlow illumination, low contrast (FIGS. 5 and 6, respectively). The Lens Alenses exhibit similar logMAR values at intermediate distances with highillumination and high contrast, and similar logMAR values at neardistances with both high illumination, high contrast, and lowillumination, low contrast.

Visual acuity measurements were actually conducted as set forth above inthis Example 3 and the results actually obtained were as predictedabove.

Thus, the Lens A lenses, which are optimally or best corrected fordistance vision in the dominant eye, and over-corrected for distancevision in the non-dominant eye, and are binocularly under-corrected forthe Add power requirement of the subjects, provide clinically acceptablenear visual acuity without compromising distance and intermediate visualacuity compared to Lens B lenses, which have an Add power that moreclosely corresponds to the Add power requirements of the present highAdd subjects.

Example 4

A similar study was conducted as described in Examples 2 and 3 with 49subjects (age range 42-65). Substantially similar results were obtainedto those described in Examples 2 and 3. For example, the results for allof the subjects demonstrated that the Lens A lenses provided improveddistance visual acuity compared to the Lens B lenses, withoutcompromising intermediate and near visual acuity (e.g., the Lens Alenses and Lens B lenses demonstrated equivalent performance forintermediate visual acuity and near visual acuity). When the data forthe subjects were grouped into Medium Add subjects (requiring an Addpower correction of +1.25 D to +1.75 D) and High Add subjects (requiringan Add power correction of +2.00 D to +2.50 D), the Lens A lensesprovided significantly improved high contrast distance visual acuitycompared to the Lens B lenses. The low contrast distance visual acuitywas significantly improved for High Add subjects, and there was noobserved significant difference in low contrast distance visual acuityfor Medium Add subjects. For high contrast intermediate visual acuity,Lens A lenses and Lens B lenses performed similarly without any observedsignificant difference. For high contrast near visual acuity, Medium Addsubjects reported similar visual acuity with Lens A lenses and Lens Blenses, and High Add subjects appeared to show a significant improvementwith Lens B lenses. For low contrast visual acuity, Lens A lenses andLens B lenses performed similarly without any observed significantdifference in visual acuity.

Although the disclosure herein refers to certain illustratedembodiments, it is to be understood that these embodiments are presentedby way of example and not by way of limitation. The intent of theforegoing detailed description, although discussing exemplaryembodiments, is to be construed to cover all modifications,alternatives, and equivalents of the embodiments as may fall within thespirit and scope of the invention as defined by the claims.

A number of publications and patents have been cited hereinabove. Eachof the cited publications and patents are hereby incorporated byreference in their entireties.

1. A method of prescribing multifocal contact lenses to a presbyopicsubject, said presbyopic subject having a dominant eye and anon-dominant eye, said method comprising: fitting a presbyopic subject,said presbyopic subject requiring an Add power correction of at least1.25 diopters (D), with a pair of multifocal contact lenses, wherein afirst multifocal contact lens of the pair comprises a first asphericpower profile derived from a first nominal aspheric power profile, and asecond multifocal contact lens of the pair comprises a second asphericpower profile derived from the first nominal aspheric power profile, butsaid second aspheric power profile providing a distance visionrefractive power offset by about +0.25 D to about +1.25 D relative tothe distance power correction for the non-dominant eye of the presbyopicsubject, whereby monocular distance visual acuity is different for eacheye with each contact lens, and binocular summation is still maintained.2. The method of claim 1, further comprising fitting a second pair ofmultifocal contact lenses to the presbyopic subject, wherein the secondpair of multifocal contact lenses comprises a first multifocal contactlens having the same aspheric power profile as the first aspheric powerprofile of the first multifocal contact lens of the first pair, and thesecond contact lens of the second pair comprises a second multifocalcontact lens having an aspheric power profile that provides an areaunder the curve that is between 5% to 45% greater than an area under thecurve of the aspheric power profile of the first multifocal contact lensof the second pair.
 3. The method of claim 2, wherein the aspheric powerprofile of the second mutifocal contact lens of the second pair providesa distance vision refractive power that is offset by about +0.25diopters to about +1.25 diopters relative to the distance powercorrection for the non-dominant eye of the presbyopic subject.
 4. Themethod of claim 1, further comprising conducting an eye examination ofthe presbyopic subject to determine which eye of the presbyopic subjectis the dominant eye.
 5. The method of claim 1, further comprisingdetermining the prescription of the presbyopic subject, and prescribingthe first and second multifocal contact lenses to the presbyopicsubject.
 6. The method of claim 1, wherein the first and secondmultifocal contact lenses so fit are each near-center asphericmultifocal contact lenses.
 7. The method of claim 1, wherein at leastone of the first multifocal contact lens and the second multifocalcontact lens so fit includes a toric optic zone effective in correctingastigmatism of the presbyopic subject.
 8. The method of claim 1, whereinthe multifocal contact lenses so fit are hydrogel or silicone hydrogelcontact lenses.
 9. The method of claim 1, further comprising providingthe multifocal contact lenses to the presbyopic subject for selfadministration by the subject.
 10. The method of claim 1, wherein thestep of administration by the subject is not claimed.